Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only

Posted by: Wet Wet Wet

Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 29/01/2011 23:17

So as we already know, Queensland is expected to be hit by 2 cyclones only a few days apart. Anthony is currently hovering in the Central Coral Sea and forecast to make landfall near Townsville early Monday morning, with the second Tropical Low currently developing to the east of Vanuatu:




Here’s the latest ECMWF run with the second cyclone forecast to make landfall at Ayr:




Forecast Winds for the potential cyclone (based on ECMWF):




And the cyclone tracking map issued by Vanuatu:



Extended Outlook:
Forecast for Wednesday
Showers and thunderstorms will continue across most of the state as the atmosphere remains moist and unstable. Showers and thunderstorms are expected to increase to thundery rain areas late in the day about the east coast and adjacent inland between about Cooktown and Bundaberg with strong to possibly gale force winds developing.

Outlook for Thursday, Friday and Saturday
Showers and thunderstorms should continue through the tropics and also over much of the interior due to a moist, unstable airflow. Instability should also increase over southeastern Queensland with showers and possible isolated thunderstorms expected. There is some potential for a new low or tropical cyclone to deepen over the Coral Sea during this outlook period which may affect tropical Queensland during Thursday. This system may then move southwest across the interior of the state during the remainder of the outlook period taking its associated rain areas with it. This situation will continue to be monitored and warnings issued as necessary.


Reasonably high tides forecasted at the time of landfall as well with a 5.71m tide in Mackay on Thursday morning.

Buckle up for a wild ride! bounce
Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 04:22

Issued at Jan 29 1700UTC / Jan 30 3:00am EST:

1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
170 NM EITHER SIDE OF A LINE FROM 14.3S 173.2E TO 15.4S 166.1E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT
IMAGERY AT 291630Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 14.3S 172.4E. THE SYSTEM IS MOVING WESTWARD AT 08 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 14.3S
172.4E IS NOW LOCATED NEAR 14.3S 172.4E, APPROXIMATELY 315 NM
NORTHEAST OF PORT VILA, VANUATU. ANIMATED INFRARED SATELLITE IMAGERY
AND A 291408Z AMSU IMAGE INDICATE INCREASING CONSOLIDATION OVER THE
PAST 12 HOURS WITH CONVECTIVE BANDING OVER THE NORTHERN SEMI-CIRCLE
WRAPPING INTO THE NORTHEAST QUADRANT. A 291031Z ASCAT IMAGE DEPICTED
A SYMMETRIC, WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
25-30 KNOT WINDS OVER THE NORTHEAST QUADRANT. OVER THE PAST 24
HOURS, THE LLCC HAS STRENGTHENED AND BECOME WELL-DEFINED. UPPER-
LEVEL ANALYSIS INDICATES THAT THE LLCC IS LOCATED UNDER AN
EXTENSION OF THE UPPER-LEVEL RIDGE WITH WEAK TO MODERATE VERTICAL
WIND SHEAR. OVERALL, THE OUTFLOW HAS IMPROVED WITH CONTINUED GOOD
EQUATORWARD OUTFLOW AND ENHANCED POLEWARD OUTFLOW DUE TO A STRONG
UPPER-LEVEL ANTICYCLONE POSITIONED JUST SOUTH OF FIJI. NUMERICAL
MODELS CONTINUE TO PREDICT SIGNIFICANT DEVELOPMENT OVER THE NEXT 24-
48 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO
30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB.
DUE TO THE IMPROVED CONSOLIDATION AND FAVORABLE UPPER LEVEL
CONDITIONS, THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS GOOD.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
301700Z.//





Lastest ASCAT:

Posted by: FNQ

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 07:48

JYWC Reissued at 291730

As area now upgraded to Good for potential development of TC

THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 14.3S
172.4E IS NOW LOCATED NEAR 14.3S 172.4E, APPROXIMATELY 315 NM
NORTHEAST OF PORT VILA, VANUATU. ANIMATED INFRARED SATELLITE IMAGERY
AND A 291408Z AMSU IMAGE INDICATE INCREASING CONSOLIDATION OVER THE
PAST 12 HOURS WITH CONVECTIVE BANDING OVER THE NORTHERN SEMI-CIRCLE
WRAPPING INTO THE NORTHEAST QUADRANT. A 291031Z ASCAT IMAGE DEPICTED
A SYMMETRIC, WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
25-30 KNOT WINDS OVER THE NORTHEAST QUADRANT. OVER THE PAST 24
HOURS, THE LLCC HAS STRENGTHENED AND BECOME WELL-DEFINED. UPPER-
LEVEL ANALYSIS INDICATES THAT THE LLCC IS LOCATED UNDER AN
EXTENSION OF THE UPPER-LEVEL RIDGE WITH WEAK TO MODERATE VERTICAL
WIND SHEAR. OVERALL, THE OUTFLOW HAS IMPROVED WITH CONTINUED GOOD
EQUATORWARD OUTFLOW AND ENHANCED POLEWARD OUTFLOW DUE TO A STRONG
UPPER-LEVEL ANTICYCLONE POSITIONED JUST SOUTH OF FIJI. NUMERICAL
MODELS CONTINUE TO PREDICT SIGNIFICANT DEVELOPMENT OVER THE NEXT 24-
48 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO
30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB.
DUE TO THE IMPROVED CONSOLIDATION AND FAVORABLE UPPER LEVEL
CONDITIONS, THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO GOOD.
Posted by: Green n Lumpy

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 10:20

TROPICAL DISTURBANCE ADVISORY NUMBER A2 ISSUED FROM RSMC NADI
Jan 29/2022 UTC 2011 UTC.

TROPICAL DEPRESSION TD09F CENTRE 1003HPA WAS LOCATED NEAR 14.3S
171.3E AT 291800 UTC. TD09F MOVING WEST AT ABOUT 11 KNOTS. POSITION
POOR BASED ON MTSAT IR IMAGERY WITH ANIMATION AND PERIPHERAL SURFACE
OBSERVATIONS. SST AROUND 29 DEGREE CELCIUS.

ORGANISATION IMPROVED SLIGHTLY PAST 12 HOURS. CONVECTION HAS
INCREASED SIGNIFICANTLY IN THE PAST 6 HOURS. SYSTEM LIES ALONG A
SURFACE TROUGH AND UNDER 250HPA RIDGE AXIS IN A WEAK SHEARED
ENVIRONMENT. CYCLONIC CIRCULATION EXTENDS TO 500HPA. SYSTEM EXPECTED
TO BE STEERED WESTWARDS MAINLY BY THE DEEP LAYER MEAN EASTERLIES.
GLOBAL MODELS ARE GRADUALLY DEVELOPING THE DEPRESSION AND MAINTAINING
A WEST-SOUTHWEST TRACK.

THE POTENTIAL FOR THIS SYSTEM TO DEVELOP INTO A TROPICAL CYCLONE IN
THE NEXT 24 TO 48 HOURS IS MODERATE TO HIGH.

THE NEXT TROPICAL DISTURBANCE ADVISORY ON TD 09F WILL BE ISSUED
AROUND 300230 UTC.

http://www.met.gov.fj/aifs_prods/20032.txt
Posted by: FNQ

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 10:50

Advisory Number 2 on a Tropical Low issued by the Vanuatu Meteorological Service, Port Vila
at 8:04am VUT Sunday 30 January 2011.

At 5:00am local time today, a tropical low (1001 hPa) was located near 14.3S 171.0E,
letter K, number 4 of the Vanuatu Tropical Cyclone Tracking Map. This is about 320 KM
east northeast of Maewo. The system is moving west southwest at 41 KM/HR. The potential
for the system to intensify into a Tropical Cyclone as well as move to the central or
northern parts of Vanuatu is the next 24 to 48 hours is moderate to high.

Forecast Positions
Date and Time Position Intensity
+06 hours (11am, 30 Jan) 14.3S, 170.6E 25 KTS (45 KM/HR)
+12 hours (5pm, 30 Jan) 14.2S, 169.9E 25 KTS (45 KM/HR)
+18 hours (11pm, 30 Jan) 14.2S, 169.2E 40 KTS (75 KM/HR)
+24 hours (5am, 31 Jan) 14.1S, 168.2E 40 KTS (75 KM/HR)
+36 hours (5pm, 31 Jan) 13.9S, 166.0E 40 KTS (75 KM/HR)
+48 hours (5am, 1 Feb) 14.0S, 163.8E 40 KTS (75 KM/HR)

Heavy rainfall is forecast to affect northern and central Vanuatu later
today. Seas are rough over the central, channel and southern waters, and a marine
strong wind warning has been issued for these areas. Seas will become very rough
with heavy swells later today. The National Disaster Management Office (NDMO) has
advised that Blue Alert is now current for Torba, Sanma, Penama and Malampa provinces.
For action on this Alert, call the National Disaster Management office (NDMO) on
telephone +678 24686 or +678 7771188.

The Vanuatu Meteorological Service will issue the next advisory on the system at
12:00pm today or earlier if the situation changes. People over Torba, Sanma, Penama and
Malampa Provinces, including Shefa are advised to listen to Radio outlets for the
latest information on this system.
Posted by: Hinezy

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 10:59

Just a little off topic but probably useful in this context..

I find this website very handy and useful in quickly comparing the different up to date model runs. (EC, GFS, CMC, JMA etc..)

For example here is CMC's take on our developing Fiji low which puts a crossing somewhere near Mackay.

CMC Latest Run
Posted by: Scottie A

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 12:36

Starting to look quite like an increasingly angry fella, latest MTSAT starting to show a clearly defined LLCC. Sure is a big system!!

Posted by: Thunderstruck

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 12:40

Yasi is going to be a big boy. Have to say that is the best looking tropical low I have ever seen. Very impressive upper divergence to the south side, excellent environment all round, should be perfect for intensification at a steady rate with pretty swift westward steering.

TS cool
Posted by: FNQ

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 13:00

Advisory Number 3 on a Tropical Low issued by the Vanuatu Meteorological Service, Port Vila
at 12:23pm VUT Sunday 30 January 2011.

At 11:00am local time today, a tropical low (1001 hPa) was located near 13.6S 170.4E,
letter J, number 3 of the Vanuatu Tropical Cyclone Tracking Map. This is about 295 KM
northeast of Maewo. The system is moving northwest at 17 KM/HR. The potential
for the system to intensify into a Tropical Cyclone as well as move to the central or
northern parts of Vanuatu is the next 24 to 48 hours is moderate to high.

Forecast Positions
Date and Time Position Intensity
+06 hours (5pm, 30 Jan) 13.1S, 169.3E 25 KTS (45 KM/HR)
+12 hours (11pm, 30 Jan) 13.0S, 168.0E 25 KTS (45 KM/HR)
+18 hours (5am, 31 Jan) 12.9S, 166.8E 40 KTS (75 KM/HR)
+24 hours (11am, 31 Jan) 12.9S, 165.2E 40 KTS (75 KM/HR)
+36 hours (11pm, 31 Jan) 12.8S, 161.9E 50 KTS (95 KM/HR)
+48 hours (11am, 1 Feb) 13.0S, 158.6E 50 KTS (95 KM/HR)

Heavy rainfall is forecast to affect northern and central Vanuatu later
today. Seas are rough over the central, channel and southern waters, and a marine
strong wind warning has been issued for these areas. Seas will become very rough
with heavy swells later today. The National Disaster Management Office (NDMO) has
advised that Blue Alert is now current for Torba, Sanma, Penama and Malampa provinces.
For action on this Alert, call the National Disaster Management office (NDMO) on
telephone +678 24686 or +678 7771188.

The Vanuatu Meteorological Service will issue the next advisory on the system at
6:00pm today or earlier if the situation changes. People over Torba, Sanma, Penama and
Malampa Provinces, including Shefa are advised to listen to Radio outlets for the
latest information on this system.
Posted by: FNQ

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 13:04

Vanuatu Track Map has it being a cat 2 by 1000 EST on 01022011;
Forecast Location for it to be a cat 2: 13 degrees S and 160 degrees E .
Posted by: mattincairns

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 14:34



WTPS31 PGTW 300300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 11P (ELEVEN) WARNING NR 001//
REF/A/NAVMARFCSTCEN PEARL HARBOR HI/291651Z JAN 11//
AMPN/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. TROPICAL CYCLONE 11P (ELEVEN) WARNING NR 001
02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
300000Z --- NEAR 13.2S 170.5E
MOVEMENT PAST SIX HOURS - 285 DEGREES AT 07 KTS
POSITION ACCURATE TO WITHIN 040 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
REPEAT POSIT: 13.2S 170.5E
---
FORECASTS:
12 HRS, VALID AT:
301200Z --- 12.6S 168.2E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 275 DEG/ 13 KTS
---
24 HRS, VALID AT:
310000Z --- 12.4S 165.5E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
075 NM SOUTHEAST QUADRANT
075 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 270 DEG/ 16 KTS
---
36 HRS, VALID AT:
311200Z --- 12.4S 162.2E
MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT
025 NM SOUTHEAST QUADRANT
025 NM SOUTHWEST QUADRANT
025 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT
035 NM SOUTHEAST QUADRANT
035 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT
085 NM SOUTHEAST QUADRANT
085 NM SOUTHWEST QUADRANT
080 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 260 DEG/ 19 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
010000Z --- 13.1S 158.4E
MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT
095 NM SOUTHEAST QUADRANT
095 NM SOUTHWEST QUADRANT
090 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 245 DEG/ 15 KTS
---
72 HRS, VALID AT:
020000Z --- 15.3S 152.8E
MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT
105 NM SOUTHEAST QUADRANT
105 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 240 DEG/ 15 KTS
---
LONG RANGE OUTLOOK:
NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM
ON DAY 4 AND 350 NM ON DAY 5... AND FOR INTENSITY
NEAR 20 KT EACH DAY.
---
96 HRS, VALID AT:
030000Z --- 18.0S 147.3E
MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 120 HR POSIT: 235 DEG/ 15 KTS
---
120 HRS, VALID AT:
040000Z --- 21.3S 142.1E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
300300Z POSITION NEAR 13.1S 169.9E.
TROPICAL CYCLONE (TC) 11P, LOCATED APPROXIMATELY 305 NM NORTH-
NORTHEAST OF PORT VILA, VANUATU, HAS TRACKED WEST-NORTHWESTWARD AT
07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS A RAPIDLY-CONSOLIDATING LOW-LEVEL CIRCULATION CENTER
(LLCC) WITH TIGHTLY-CURVED CONVECTIVE BANDING WRAPPING INTO A WELL-
DEFINED CENTER. RECENT MICROWAVE IMAGERY IS UNAVAILABLE, HOWEVER, A
291814Z CORIOLIS 36H IMAGE ALSO SUPPORTED THE RAPID DEVELOPMENT AND
DEPICTED MULTIPLE CONVECTIVE BANDING AND A SMALL MICROWAVE EYE
FEATURE. A 292139Z ASCAT IMAGE SHOWED 30-35 KNOT WINDS NEAR THE
CENTER. THE CURRENT INTENSITY IS BASED ON THE IMPRESSIVE SATELLITE
SIGNATURE AS WELL AS THE CORRESPONDING DVORAK ESTIMATES OF 35 KNOTS
FROM PGTW AND PHFO. UPPER-LEVEL ANALYSIS INDICATES THAT THE LLCC IS
LOCATED UNDER AN ANTICYCLONE WITH WEAK VERTICAL WIND SHEAR (VWS).
ANIMATED WATER VAPOR IMAGERY DEPICTED EXCELLENT RADIAL OUTFLOW. TC
11P IS CURRENTLY TRACKING ALONG THE NORTHERN PERIPHERY OF THE DEEP
SUBTROPICAL RIDGE (STR) POSITIONED TO THE SOUTH. THE SYSTEM IS
EXPECTED TO TRACK GENERALLY WESTWARD THROUGH TAU 48 THEN TURN WEST-
SOUTHWESTWARD TO SOUTHWESTWARD IN THE LATER TAUS. THE STR IS
EXPECTED TO MAINTAIN THROUGH THE PERIOD BUT WILL SHIFT EAST AND RE-
ORIENT AS A MIDLATITUDE SHORTWAVE TROUGH DEEPENS OVER CENTRAL
AUSTRALIA AFTER TAU 72. THE AVAILABLE MODEL GUIDANCE IS LIMITED BUT
IS TIGHTLY CLUSTERED THEREFORE THERE IS GOOD CONFIDENCE IN THE
TRACK. THE ECMWF TRACKER IS UNAVAILABLE BUT THE 29/12Z MODEL FIELDS
ARE IN CLOSE AGREEMENT WITH THE MODEL CONSENSUS. THIS FORECAST TRACK
IS BASED LARGELY ON THE CONSENSUS. BASED ON THE FAVORABLE CONDITIONS
THROUGHOUT THE FORECAST PERIOD AND THE RECENT INTENSIFICATION TREND,
TC 11P IS EXPECTED TO INTENSIFY AT A 20-25 KNOT RATE PER DAY THROUGH
TAU 72 AND AT A SLOWER RATE UNTIL MAKING LANDFALL NEAR TAU 96. THERE
IS POTENTIAL FOR THIS SYSTEM TO PEAK HIGHER THAN 110 KNOTS AND MAKE
LANDFALL AS A VERY STRONG, LARGE SYSTEM. THIS WARNING SUPERSEDES AND
CANCELS REF A, NAVMARFCSTCEN 291651Z JAN 11 TROPICAL CYCLONE
FORMATION ALERT (WTPS21 PGTW 291700). MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 300000Z IS 11 FEET. NEXT WARNINGS AT 301500Z AND 310300Z.
REFER TO TROPICAL CYCLONE 09P (ANTHONY) WARNINGS (WTPS32 PGTW)
FOR TWELVE-HOURLY UPDATES.//
NNNN
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 14:51

This one looks very very nasty indeed. lots of time to develop and lots of momentum. A big area of relative3ly low shear is sitting in Anthony's wake for this one. SST's are not incredible (~27-29C mark) but enough.
Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 15:10

Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 16:20

Ge she is developing fast and big, surely close to naming!
Compare the size of this system to little Anthony in the full disk image


JTWC has 110kt sustained and 135kt gusts, that puts this one firmly in the Cat 4 range and possibly pushing Cat 5!
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 16:44

She has been named TC Yasi- Mods please change the title of this thread.
Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 18:46

Queensland State Forecast & Extended Outlook:

Issued at 4:15 pm EST on Sunday 30 January 2011

A Cyclone Warning is current for coastal and island communities from Cardwell to Sarina. A Strong Wind Warning is current for remaining coastal waters between Innisfail and Burnett Heads. A flood warning is current for the Balonne River. A flood warning is current for coastal rivers and streams between Townsville and Sarina and adjacent inland catchments.

Weather Situation
A weak monsoon trough extends from Torres Strait to Tropical Cyclone Anthony over the western Coral Sea. A high over the Tasman Sea extends a firm ridge along the east Queensland coast. Tropical Cyclone Yasi has been named near Vanuatu in the eastern Coral Sea and is likely to affect the Queensland coast from Wednesday and the adjacent interior from Thursday through to the weekend. This situation will be closely monitored and warnings issued as necessary during the week.

Forecast for the rest of Sunday
Scattered showers and isolated thunderstorms over the tropics and far north-western Queensland, increasing to squally rain and thunderstorms about the central and southern tropical coast and adjacent inland late in the day and overnight with moderate to heavy falls. Scattered showers about the remaining east coast, tending isolated over the adjacent inland and the far southeast. Moderate to locally fresh SE to NE winds, strong and gusty about the tropical coast and reaching gale to storm force about the central and southern tropical coast in the evening and overnight.

Forecast for Monday
Tropical Cyclone Anthony is expected to cross the Burdekin Coast south of Ayr close to midnight. Please refer to the latest products from the Tropical Cyclone Warning Centre for the latest information. Showers and isolated thunderstorms are expected over the far northern tropics. Heavier rain areas and thunderstorms associated with the cyclone are expected elsewhere along the southern tropical and central coasts, and should also extend inland into the tropical and central interior. Cloud should increase over western Queensland with patchy light rain and showers developing later in the day. Mostly fine conditions in the southeast with only isolated showers expected. Tropical Cyclone Yasi is expected to be moving steadily westwards.

Forecast for Tuesday
The remnant of cyclone Anthony is expected to have weakened to a deep low over the central interior, moving towards the southwest of the state. Showers and isolated thunderstorms are expected over the northern tropics and central districts in the wake of the system, increasing to areas of rain and isolated thunderstorms over the southwest. Isolated showers over southeast districts, scattered along the coast with possible thunderstorms over inland parts. Isolated showers and thunderstorms over the northwest. Tropical Cyclone Yasi is expected to be moving west over the central Coral Sea region.

Forecast for Wednesday
Showers and thunderstorms will continue across most of the state as the atmosphere remains moist and unstable. Showers and thunderstorms are expected to increase to thundery rain areas during the day about the east coast and adjacent inland between about Cooktown and Bundaberg with strong to possibly gale force winds developing due to the approach of Tropical Cyclone Yasi.

Forecast for Thursday
Tropical Cyclone Yasi is likely to make landfall on the Queensland east coast as a large and strong system. The most likely area of crossing is again the tropical coast although the potential exists for a crossing further north or south. Storm to hurricane force winds and very heavy rainfall are likely to accompany the passage of Tropical Cyclone Yasi, and extend inland during the day to the adjacent interior. Scattered showers and isolated thunderstorms persisting over the west of the state. Scattered showers about the southeast and isolated showers over the southern interior.

Outlook for Friday, Saturday and Sunday
Tropical Cyclone Yasi should continue to move west across the state, slowly weakening and reaching the western border over the weekend. Gale force winds and heavy rains will accompany the system. Showers and thunderstorms should continue elsewhere through the tropics and the interior due to the moist, unstable airflow. Scattered showers will persist over southeast Queensland.

The next routine forecast will be issued at 4:45 am EST Monday.
Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 19:27

Latest ECMWF forecast has Yasi making landfall directly over Home Hill (Half way between Bowen and Townsville):

Posted by: H'Bay Qld

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 19:36

Originally Posted By: Wet Wet Wet


My God that this is a monster. The area it covers is enormous!
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 19:39

Still fairly disorganised, but bloody massive and down to 993hPa already. Yasi is already creating her own low shear environment, but could be affected slightly as it passes over the islands near Vanuatu. Once it has cleared them it should intensify fairly rapidly if it maintains its own low shear environemnt.



Most of the dynamical models have it crossing further south than the JTWC map.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 19:47

Originally Posted By: H'Bay Qld
Originally Posted By: Wet Wet Wet


My God that this is a monster. The area it covers is enormous!
It is still a baby so will probably consolidate over the enxt few days as it gets itself more organised, but yes, it does look huge! Often the smallest storms pack the biggest punches, as they are more tightly "wound up" for want of a better term.
Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 21:27



Forecast Landfall locations for Jan 30 00UTC:
GFS – Cardwell
UKMET – Townsville
ECMWF – Home Hill
NOGAPS – Bowen
CMC – Sarina
Posted by: Dodger

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 30/01/2011 21:27

Ok latest multi. Tighter looking than 2 hours ago. Flows a little bit more organised. I want to put comparison up at cat 2 call.
Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 05:32

Models in good agreement of a coastal impact from a Severe Tropical Cyclone. I urge all people between Cairns and Bundaberg (Particularly Townsville to Mackay) to take this threat VERY SERIOUSLY.

At the moment consensus is for landfall to occur between about Cardwell and Sarina. Personally I have a strong feeling Yasi will take a SW track when nearing the coast ending up in the Mackay to Proserpine region. Now I don’t mind being in a cyclone, but only when winds are below 150km/h. Once you start talking 250km/h+ the consequences are devastating and potentially lethal.

It’s been 93 years since Mackay was devastated by a Catergory 4/5 cyclone, and I’m afraid I think our number is up once again.

Stay Safe Everyone.....
Posted by: Dodger

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 07:57

Even CMC have moved there track north from previous.



She certainly got her skates on last night.
Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 08:52

Latest Forecast Track Map from the Fiji Met:

Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 10:03

Comparing the 1930UTC and 2030UTC satellite images, Yasi has taken a WSW track with the centre dropping from latitude 13.5S to 13.8S. Latest model run from GFS has coastal impact over Townsville, whereas NOGAPS has forecasted a more northerly crossing point with landfall at Innisfail.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 10:36

Latest JTWC track map has pushed the crossing further south in line with the dynamical models, so they all pretty much agree now


And the latest microwave shots show a much more organised storm with a well defined covered LLCC, good centralisation of the CDO (well it is getting there anyway!) and an internal eye forming.


It will be interesting to watch how tight it becomes today.
Posted by: Kate_B

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 11:59

Latest track map for Yasi

Posted by: Kate_B

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 12:10

Previous track map from 8:55am VUT

Posted by: Squeako da Magnifico.

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 12:18

Tropical Cyclone Warning Number 8 for Torba, Sanma, Penama and Malampa Provinces.

Tropical Cyclone Warning Number 8 issued by the Vanuatu Meteorological Service, Port Vila
at 12:08pm VUT Monday 31 January 2011 for Torba, Sanma, Penama and Malampa Provinces.

At 11:00am local time today, Tropical Cyclone Yasi was located near
13.5 degrees South 164.4 degrees East, square letter D, number 3 (D, 3) of the Vanuatu
tropical cyclone tracking map. This is about 240 KM west of Torres and 290 KM west northwest
of Santo. The Tropical Cyclone moved in a west direction at 27 KM/HR (15 knots) in the
past 6 hours.

The central pressure of the system is estimated at 984 hPa. Winds close to the centre
estimated at 95 KM/HR (50 knots), possibly increasing to 110KM/HR (60 KTS) in the next
12 hours. The Tropical Cyclone is forecast to be at 13.9 degrees South 161.0 degrees East
within the next 06 to 12 hours. Destructive Storm force winds of 90KM/HR, gusting to
130KM/HR will affect Torba, Sanma, Penama and Malampa Provinces in the next
6 to 12 hours.

Winds of 40 to 50 KM/HR may still affect Shefa province today and possibly increasing
to marginal gale of 60KM/HR as the system moves away from Torba and Sanma provinces.

Forecast Positions
Date and Time Position Intensity
+06 hours (5pm, 31 Jan) 13.6S, 162.8E 50 KTS (95 KM/HR)
+12 hours (11pm, 31 Jan) 13.9S, 161.0E 50 KTS (95 KM/HR)
+18 hours (5am, 1 Feb) 14.1S, 159.3E 70 KTS (130 KM/HR)
+24 hours (11am, 1 Feb) 14.6S, 157.7E 70 KTS (130 KM/HR)
+36 hours (11pm, 1 Feb) 15.7S, 154.5E 70 KTS (130 KM/HR)
+48 hours (11am, 2 Feb) 17.0S, 151.5E 70 KTS (130 KM/HR)
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 12:28

I believe Brisbane's AOR is at 160°E so that means she should enter Australian "metspace" later today.

The satellite data is predicting an area of reasonably high shear over the next 10hrs or so, which will probably limit growth. I'd love to see a technical forecast or does the RSMC Fiji not issue them?
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 13:17

Jesus! Not often you see a single storm take up an ENTIRE single frame MODIS shot!!!

Below is the raw 2km resolution MODIS image from Terra at 23:18Z 30/1/2011 (about 4hrs ago). Click on this image for the full 250m resolution MODIS shot (VERY large).

Posted by: jtc

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 13:37

Latest JTWC track Warning #3

http://www.usno.navy.mil/NOOC/nmfc-ph/RSS/jtwc/warnings/sh1111.gif

Puts max sus winds at 213 km/h with gusts up to 260 km/h (offshore)

Max sus Winds @ 185 km/hr during landfall
Posted by: Kate_B

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 13:39

Posted by: Kate_B

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 13:42

IDQ20018
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 0228 UTC 31/01/2011
Name: Tropical Cyclone Yasi
Identifier: 14U
Data At: 0000 UTC
Latitude: 13.6S
Longitude: 164.2E
Location Accuracy: within 30 nm [55 km]
Movement Towards: west [270 deg]
Speed of Movement: 17 knots [31 km/h]
Maximum 10-Minute Wind: 55 knots [100 km/h]
Maximum 3-Second Wind Gust: 75 knots [140 km/h]
Central Pressure: 980 hPa
Radius of 34-knot winds NE quadrant: 150 nm [280 km]
Radius of 34-knot winds SE quadrant: 150 nm [280 km]
Radius of 34-knot winds SW quadrant: 90 nm [165 km]
Radius of 34-knot winds NW quadrant: 80 nm [150 km]
Radius of 48-knot winds NE quadrant: 20 nm [35 km]
Radius of 48-knot winds SE quadrant: 20 nm [35 km]
Radius of 48-knot winds SW quadrant: 20 nm [35 km]
Radius of 48-knot winds NW quadrant: 20 nm [35 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T3.5/3.5/D1.0/24HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 200 nm [370 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 31/1200: 13.9S 160.5E: 060 [110]: 070 [130]: 973
+24: 01/0000: 14.6S 157.2E: 090 [165]: 080 [150]: 965
+36: 01/1200: 15.6S 154.0E: 120 [225]: 085 [155]: 961
+48: 02/0000: 16.9S 151.0E: 155 [285]: 095 [175]: 951
+60: 02/1200: 18.0S 148.1E: 200 [375]: 100 [185]: 942
+72: 03/0000: 19.3S 145.3E: 250 [465]: 060 [110]: 977
REMARKS:
Curved band 0.7 on MTSAT VIS at 2330UTC gives a DT of 3.5. Outflow increasing
further to north and system is showing better organisation with persistent deep
convection near its centre. TC is expected to enter a favourable environment for
intensification and ridge to south is expected to steer it towards the west
southwest rapidly.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 31/0700 UTC by Brisbane
TCWC.
Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 13:47

The storm surge produced by Yasi could be a major problem. As has been already mentioned, there are reasonably high tides Thursday morning:

2.75m – Port Douglas
2.96m – Cairns
2.89m – Mourilyan
3.37m – Lucinda
3.49m – Townsville
3.03m – Abbot Point
5.71m – Mackay
6.20m – Hay Point
5.23m – Port Alma
4.23m – Gladstone

A large and intense system like Yasi will have low pressure spread over a large portion of the ocean. Lower pressure = higher sea levels. Combine that with very strong easterly winds extending several hundred kilometres (forcing more water towards the coast), a fast moving cyclone heading directly at the coastline and very large waves….we could see a storm surge several metres higher than the expected high tide.

I mentioned this last year prior to Ului coming ashore, but I’ll say it again: in the 1918 cyclone that hit Mackay, the storm surge extended several kilometres inland with witnesses reporting waves 2.7m high breaking in the main street. As a result it was decided no future houses would be allowed to be built on the land east of ‘Juliet St’ as this area was flooded several metres deep by the storm surge. But memories must be short because today there are thousands of houses built on this area once earmarked forbidden.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 13:58

Yes and the quadrant to the south of the eye is the most vulnerable as it will have the highest winds and the largest seas. Next decent (SSMIS) sensor pass will be on F17 at 03:40Z, so no decent scans for another hour or two.
Posted by: Subtropical

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 14:32

Originally Posted By: Wet Wet Wet
The storm surge produced by Yasi could be a major problem. As has been already mentioned, there are reasonably high tides Thursday morning:

2.75m – Port Douglas
2.96m – Cairns
2.89m – Mourilyan
3.37m – Lucinda
3.49m – Townsville
3.03m – Abbot Point
5.71m – Mackay
6.20m – Hay Point
5.23m – Port Alma
4.23m – Gladstone

A large and intense system like Yasi will have low pressure spread over a large portion of the ocean. Lower pressure = higher sea levels. Combine that with very strong easterly winds extending several hundred kilometres (forcing more water towards the coast), a fast moving cyclone heading directly at the coastline and very large waves….we could see a storm surge several metres higher than the expected high tide.

I mentioned this last year prior to Ului coming ashore, but I’ll say it again: in the 1918 cyclone that hit Mackay, the storm surge extended several kilometres inland with witnesses reporting waves 2.7m high breaking in the main street. As a result it was decided no future houses would be allowed to be built on the land east of ‘Juliet St’ as this area was flooded several metres deep by the storm surge. But memories must be short because today there are thousands of houses built on this area once earmarked forbidden.


Gday WWW. Thanks for the interesting historical info on Juliet St Mackay. That's a very useful guide for anyone who is located close to the coast in the event of a cyclone.

Some added info, Juliet St Mackay, according to Google Earth, is 4 metres above sea level and 2 km inland from the coast.

Here's some useful info... Tropical Cyclone Scales, that includes storm surge heights related to cyclone category ratings.
Posted by: yankeedownunder

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 14:42

Warning issued - one liner in Tech thread.

Please keep within guidelines:

http://forum.weatherzone.com.au/ubbthreads.php/topics/793961/Technical_Reports_threads#Post793961

Cheers

WZ Moderators
Posted by: Roy G Biv

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 14:58

Please do not post one line links in here. Feel free to post an image with comments - if you want to post one liners use the chat thread.

You'll find guidelines here:

http://forum.weatherzone.com.au/ubbthreads.php/topics/793961/Technical_Reports_threads#Post793961

Cheers

WZ Moderators
Posted by: Mick10

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 15:01

TROPICAL CYCLONE ADVICE NUMBER 1
Issued by the Bureau of Meteorology, Brisbane
Issued at 1:52pm EST on Monday the 31st of January 2011

A Cyclone WATCH has been declared for coastal and island communities from
Cooktown to Yeppoon.

At 1:00 pm EST Tropical Cyclone Yasi, Category 2 was estimated to be
1880 kilometres east northeast of Townsville and 1730 kilometres east northeast
of Mackay moving west at 30 kilometres per hour.

The cyclone is expected to intensify as it moves west over the Coral Sea.

Damaging winds are expected to develop about coastal and island communities
between Cooktown and Yeppoon Wednesday morning.

People between Cooktown and Yeppoon should consider what action they will need
to take if the cyclone threat increases.

- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Tropical Cyclone Yasi at 1:00 pm EST:
.Centre located near...... 13.6 degrees South 163.4 degrees East
.Location accuracy........ within 35 kilometres
.Recent movement.......... towards the west at 30 kilometres per hour
.Wind gusts near centre... 150 kilometres per hour and INTENSIFYING
.Severity category........ 2
.Central pressure......... 975 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 5:00 pm EST Monday 31 January.
Posted by: !SCHUMMY!

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 15:43

Here is the latest Track Map from the BoM



this one is gonna be serious, i wouldnt be surprised to see a cat 5 on their track maps soon....

also those very destructive winds extend along way out from the centre on the southern/south-eastern quadrants
Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 15:56



I thought I’d post this track map as the other one posted above it will continue to update forever into the future as it has not been uploaded to an image hosting site.

I could be wrong here, but this is possibly the first time ever parts of Queensland have been on a Cyclone Watch/Warning for 2 different systems less than 24hrs apart following the passage of Anthony yesterday.



Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 16:04

Originally Posted By: opplevelse
Yes and the quadrant to the south of the eye is the most vulnerable as it will have the highest winds and the largest seas. Next decent (SSMIS) sensor pass will be on F17 at 03:40Z, so no decent scans for another hour or two.
my bad I was looking at the closest point of approach which was 340km not the actually overpass time blush oops, F17 actually is due at 06:37Z in about 1:40hr, the TRMM pass will be too far away, so we'll just have to wait for F17.

That BoM track map is interesting in that it has really downplayed the winds in the north quadrant, which I assume is primarily becuase of the storms bulk motion?
Posted by: markj23

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 16:22

im willing to host any images/maps in relation to Yasi, just so the info isn't spread out/lost by any image hosts in the future

feel free to PM me and i can provide email details, or provide you with FTP details to upload yourself
Posted by: Popeye

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 16:25

Picture taken about 2 hours ago approx. Yasi is looking nice out there.


In a very basic summary of what is going to steer Yasi is in the Picture below. She should slide West maybe a little WSW along the top of those lovely white contoured lines and then roll off the edge nearing the coast to slide down to the SW at, before or after landfall (this may happen after landfall though as those lovely white contoured lines could stay their until landfall.) Please tell me if that wrong anyone. Which is a way to understand what the big guns are saying below.

TC 11P (YASI) IS TRACKING ALONG THE NORTHERN PERIPHERY OF A DEEP
SUBTROPICAL RIDGE (STR) POSITIONED TO THE SOUTH. THE SYSTEM IS
EXPECTED TO TRACK WEST-SOUTHWESTWARD THROUGH TAU 72 (the next 72hours). THE STR IS
EXPECTED TO MAINTAIN THROUGH THE PERIOD BUT WILL SHIFT EAST AND RE-
ORIENT AS A MIDLATITUDE SHORTWAVE TROUGH DEEPENS OVER CENTRAL
AUSTRALIA AFTER TAU 72 (after 72 hrs). THIS WILL ALLOW THE SYSTEM TO TURN
SOUTHWESTWARD AFTER MAKING LANDFALL NEAR TAU 72.
Posted by: Hinezy

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 16:26

Sorry if this image is oversize.. but here's a Hi-Res pic..

Posted by: Popeye

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 16:38

My undersatnding also is that intense systems are steered high in the uppers whereas Smaller CAT1+2s are steered closer to the surface. Can anyone see any insights into what Upper atmosphere systems will come into play that might give a little shift here or there or is it going to be straightine Steering WSW to the coast.
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 16:54

Originally Posted By: Popeye
My undersatnding also is that intense systems are steered high in the uppers whereas Smaller CAT1+2s are steered closer to the surface. Can anyone see any insights into what Upper atmosphere systems will come into play that might give a little shift here or there or is it going to be straightine Steering WSW to the coast.


GFS +12hrs, that low to the right of SEQ is set to take over and head E into the over SEQ, hence South steering!


GFS +24hrs


GFS +36hrs
Posted by: Mad Elf #1

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 17:04

So, is it possible Yasi slipping further south if that high pressure system moves over?
I suppose it will have to slow down a tad. Or is there some other influence that can bring it further
south toward SEQ??
Posted by: Blueycairns

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 17:26

Sorry TC Poncho didnt understand that too well. The low looks to be heading west not east, am I looking at the right low? The High looks to be heading east.
Still trying to work out the steering influences.
Re Popeyes steering post above(it looks to be the the 400-850mb layer) why would the system not move in a NW direction with the flow?
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 17:58

I wont put this one up as it is a lower resolution multi (from SSMI) and the SSMIS one is due fairly soon. Dosent show much new info anyway, although the eye seems to be much tighter ... although that could just be the resolution considering the size of the system:
http://www.nrlmry.navy.mil/tcdat/tc11/SH...-1625E.83pc.jpg

Still fully covered eye, but CDO will centrallised now over LLCC .... waiting for F17 to come up! smile
Posted by: SGB

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 18:02

Imo TC Yasi looks to be heading SW now, mainly due to the convection on its southern flank. The way I understand it, is that the area of strongest convection is usually the direction the cyclone is headed, due to compression as the cyclone pushes against the atmosphere.

Please someone correct me if I'm wrong about this.
Posted by: Mick10

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 18:03

PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 2
Issued by the Bureau of Meteorology, Brisbane
Issued at 5:02pm EST on Monday the 31st of January 2011

A Cyclone WATCH has been declared for coastal and island communities from
Cooktown to Yeppoon.

At 4:00 pm EST Severe Tropical Cyclone Yasi, Category 3 was estimated to be
1780 kilometres east northeast of Townsville and 1630 kilometres east northeast
of Mackay moving west at 30 kilometres per hour.

The cyclone is expected to intensify as it moves west over the Coral Sea.

Damaging winds are expected to develop about coastal and island communities
between Cooktown and Yeppoon Wednesday morning.

People between Cooktown and Yeppoon should consider what action they will need
to take if the cyclone threat increases.

- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 4:00 pm EST:
.Centre located near...... 13.8 degrees South 162.5 degrees East
.Location accuracy........ within 35 kilometres
.Recent movement.......... towards the west at 30 kilometres per hour
.Wind gusts near centre... 185 kilometres per hour and INTENSIFYING
.Severity category........ 3
.Central pressure......... 970 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 11:00 pm EST Monday 31 January.
Posted by: Things

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 18:04

BoM just pushed it a little further North now!

Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 18:14

Presumably the distortion in the wind radii are due to the fast speed of the cyclone? Has anyone ever seen this before with other cyclone tracking maps or is this a new BoM tracking aid? Most interesting. Any ideas?

If it was due to frictional effects of the land then it would only occur when the cyclone neared the coast, not right out to sea.

The revision to the north is very interesting and possibly reflects Yasi's greater than expected forward speed. This putting the Cardwell-Tully area in the firing line at this stage.

I see it will be a borderline Cat. 5 on landing:FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 31/1800: 13.9S 158.8E: 050 [095]: 085 [155]: 957
+24: 01/0600: 15.0S 155.6E: 080 [150]: 095 [175]: 947
+36: 01/1800: 16.0S 152.3E: 110 [210]: 095 [175]: 945
+48: 02/0600: 17.2S 149.2E: 145 [270]: 100 [185]: 939
+60: 02/1800: 18.6S 146.4E: 190 [355]: 105 [195]: 926
+72: 03/0600: 20.0S 143.6E: 240 [445]: 050 [095]: 982
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 18:18

Originally Posted By: BoM Technical Update

IDQ20018
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 0656 UTC 31/01/2011
Name: Severe Tropical Cyclone Yasi
Identifier: 14U
Data At: 0600 UTC
Latitude: 13.8S
Longitude: 162.5E
Location Accuracy: within 20 nm [35 km]
Movement Towards: west [263 deg]
Speed of Movement: 17 knots [31 km/h]
Maximum 10-Minute Wind: 75 knots [140 km/h]
Maximum 3-Second Wind Gust: 100 knots [185 km/h]
Central Pressure: 970 hPa
Radius of 34-knot winds NE quadrant: 150 nm [280 km]
Radius of 34-knot winds SE quadrant: 175 nm [325 km]
Radius of 34-knot winds SW quadrant: 120 nm [220 km]
Radius of 34-knot winds NW quadrant: 80 nm [150 km]
Radius of 48-knot winds NE quadrant: 50 nm [95 km]
Radius of 48-knot winds SE quadrant: 80 nm [150 km]
Radius of 48-knot winds SW quadrant: 45 nm [85 km]
Radius of 48-knot winds NW quadrant: 20 nm [35 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T4.5/4.5/D1.5/24HRS
Pressure of outermost isobar: 1000 hPa
Radius of outermost closed isobar: 180 nm [335 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 31/1800: 13.9S 158.8E: 050 [095]: 085 [155]: 957
+24: 01/0600: 15.0S 155.6E: 080 [150]: 095 [175]: 947
+36: 01/1800: 16.0S 152.3E: 110 [210]: 095 [175]: 945
+48: 02/0600: 17.2S 149.2E: 145 [270]: 100 [185]: 939
+60: 02/1800: 18.6S 146.4E: 190 [355]: 105 [195]: 926
+72: 03/0600: 20.0S 143.6E: 240 [445]: 050 [095]: 982
REMARKS:
Curved band 1.45 on MTSAT VIS at 0530UTC gives a DT of 4.5. Outflow increasing
further to north and starting to now increase to the south. System is showing
increased organisation with persistent deep convection near its centre. TC is
entering a favourable environment for intensification and ridge to south is
expected to steer it rapidly towards the west southwest.

Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 18:20

Originally Posted By: Stevo59
Presumably the distortion in the wind radii are due to the fast speed of the cyclone? Has anyone ever seen this before with other cyclone tracking maps or is this a new BoM tracking aid? Most interesting. Any ideas?...
Yep that is what I said earlier. It is odd, you do not normally see it so pronounced, but the shape of the "divot" for want of a better term, is consistant with what you would get if bulk motion WRT land was the reason.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 18:32


Much tighter
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 18:39

Originally Posted By: Blueycairns
Sorry TC Poncho didnt understand that too well. The low looks to be heading west not east, am I looking at the right low? The High looks to be heading east.
Still trying to work out the steering influences.
Re Popeyes steering post above(it looks to be the the 400-850mb layer) why would the system not move in a NW direction with the flow?


yeah sorry, I ment the low was heading west towards the SEQ while the high is moving east. You are right grin

with Popeyes chart, your more looking at the high well below the TC indicated on the map
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 18:43

Originally Posted By: Things
BoM just pushed it a little further North now!



but they have pushed the base point more to the WSW from the last one?
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 18:46

Bugger was expanding on my post when the time expired!

anyway ... still has quite a bit of consolidation to do, with a small fairly thin eyewall. Lovely CDO with covered eye.

Next decent MW shot will be from F16 at 7:51Z, but that is a lot of convection in the East quadrant which will wrap around the eye.
Posted by: MareebaWeather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 20:00

Online scanner feeds from Far North Queensland
RadioReference Feeds

---------------------------

Cyclone

Live Weather Data & Lightning Tracker
Posted by: marakai

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 22:03

Hi All

Just been staring at the MTSAT water Vapor loop for a while and cant help thinking that Yasi is riding the wave of the upper low at 160E. Is this the case? I notice the hollow behind this upper low and am wondering if this was what was expected to drop Yasi to the SW but instead Yasi has been riding the top of the wave so to speak.

If this is the case is there the chance that Yasi will continue to ride the wave and be delivered to the coast at a higher level up the Cape than expected so far, and is the reason for Yasi creeping higher on each of the latest model runs IE staying/running ahead of the upper low rather than falling down behind it?

Sorry for the rudimentary questions on the Tech thread but I am trying to grasp the fundamentals of steering and the other thread is headless Chook territory at the moment.
Posted by: MikeM

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 22:19

On the last frame it looks like it has started a south west turn, but to confirm this, we have to see the next frame. If thats he case then a crossing much further south would be anticipated. I think that as yasi gets bigger it will be able to steer itself as seen before with the bigger systems, so really the only thing at the moment is the models for the best guess.
Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 22:30

Originally Posted By: MikeM
On the last frame it looks like it has started a south west turn, but to confirm this, we have to see the next frame. If thats he case then a crossing much further south would be anticipated. I think that as yasi gets bigger it will be able to steer itself as seen before with the bigger systems, so really the only thing at the moment is the models for the best guess.


I cannot see a SW turn as this stage, if anything more towards the WNW or slighly north of a true W track. At first, I though this was some convection wrapping around the LLCC from the south giving the impression of a turn to the WNW. I am now not so sure. Let's wait for a few more frames.

It could be just a wobble and the general trend is still more or less west.

Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 23:03

Latest UKMet going for a more northern crossing (just north of Innisfail). They kick in the WSW trend after about 150E:

FXXT01 EGRR 310600


MET OFFICE TROPICAL CYCLONE GUIDANCE FOR SOUTH PACIFIC AND

SOUTH-EAST INDIAN OCEANS

GLOBAL MODEL DATA TIME 00UTC 31.01.2011

TROPICAL CYCLONE YASI ANALYSED POSITION : 13.8S 164.1E

VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
00UTC 31.01.2011 13.8S 164.1E MODERATE
12UTC 31.01.2011 13.7S 160.9E STRONG INTENSIFYING SLIGHTLY
00UTC 01.02.2011 14.2S 157.3E STRONG INTENSIFYING SLIGHTLY
12UTC 01.02.2011 14.4S 153.5E STRONG LITTLE CHANGE
00UTC 02.02.2011 15.1S 150.7E STRONG LITTLE CHANGE
12UTC 02.02.2011 16.2S 148.1E STRONG LITTLE CHANGE
00UTC 03.02.2011 17.4S 145.8E STRONG LITTLE CHANGE
12UTC 03.02.2011 18.4S 142.5E WEAK WEAKENING SLIGHTLY
00UTC 04.02.2011 19.1S 139.3E BELOW TROPICAL STORM STRENGTH

THIS INFORMATION IS PROVIDED AS GUIDANCE FOR TROPICAL CYCLONE
RSMCS. IT REQUIRES INTERPRETATION BY TROPICAL CYCLONE SPECIALISTS
AND SHOULD NOT BE CONSIDERED AS A FINAL PRODUCT

MET OFFICE, EXETER, UK

TOO 310437


Posted by: astrogirl

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 23:15

This was posted in the chat thread, and promptly lost behind pages as that one is moving so fast. Its American but gives a good summary and analysis and will probably be useful to those who (like me) check this thread for information and appreciate not having to scroll through loads of other discussion.

http://www.youtube.com/user/robcenter1#p/a/u/0/PT1bmcv7GL4

I am also interested to hear from the more experienced and knowledgeable as to whether you agree, disagree etc!
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 23:18

Originally Posted By: Cyclone
Online scanner feeds from Far North Queensland
RadioReference Feeds

---------------------------

Cyclone

Live Weather Data & Lightning Tracker

Thanks, that will be interesting, and is appreciated.
No updated MW scans, but the IR indicates perhaps a little more consolidation but still has the CDO covering the eye, although I would expect that to change overnight as it intensifies slightly (assuming the shear stays low).

Yasi is still seems to be creating its own low shear environment. But with moderate vertical shear to the west it will be interesting to see how it powers through.


Interestingly the technical bulletin makes no mention of the 20-30kt shear so the experts must thing it will just power through creating its own little hole as it goes.
Posted by: MikeM

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 31/01/2011 23:30

Astrogirl, that was probably the most blunt and descriptive message on yasi i have seen. Very informative and %100 for presentation. Much better than listening to anna give her third, fourth, fith hand description. Anyone else who wants to watch this excellent technical discussion please use astro's link
Posted by: Mick10

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 00:04

TOP PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 3
Issued by the Bureau of Meteorology, Brisbane
Issued at 11:02pm EST on Monday the 31st of January 2011

A Cyclone WATCH has been declared for coastal and island communities from
Cooktown to Yeppoon and inland to between Georgetown and Moranbah.

At 10:00 pm EST Severe Tropical Cyclone Yasi, Category 3 was estimated to be
1610 kilometres east northeast of Townsville and 1490 kilometres northeast of
Mackay moving west at 30 kilometres per hour.

The cyclone is expected to intensify as it moves west over the Coral Sea.

Damaging winds are expected to develop about coastal and island communities
between Cooktown and Yeppoon Wednesday morning, and about adjacent inland parts
on Wednesday afternoon.

People between Cooktown and Yeppoon should consider what action they will need
to take if the cyclone threat increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 10:00 pm EST:
.Centre located near...... 13.4 degrees South 160.6 degrees East
.Location accuracy........ within 55 kilometres
.Recent movement.......... towards the west at 30 kilometres per hour
.Wind gusts near centre... 205 kilometres per hour and INTENSIFYING
.Severity category........ 3
.Central pressure......... 963 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 5:00 am EST Tuesday 01 February.
Posted by: Things

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 00:06

Even further North now!

Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 00:14

Thanks astro girl! Pretty much what we've been saying here (I wonder if he's been reading this thread wink ) smile , with cyclones of this size I do prefer to look at the high-scale microwave imagery as it tends to show details the standard scale doesnt. What he showed was the standard scale image, which just looked like a big blob smile

For example the latest MW imagery at the lower scale just shows a big red blob (high brightness "temperature" ) near the LLCC
http://www.nrlmry.navy.mil/tcdat/tc11/SH...-1625E.96pc.jpg
But the same scan with the high scaling applied makes it much easier to discern features ...


FWIW this scan does not show any clear eye structure like the previous ones. It may be because the scan was at a lower resolution for some reason but I dont recall the SSMI-S sensor on F18 to be any different to that on F17 so ??? I guess the eyewall has just vanished, perhaps an ERC, but hard to tell since the CDO has always covered the eye (see IR shot below)
Posted by: Rainwoman_08

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 00:19

I wonder has this system gone through an eye wall replacement already, due to instenfying so rapidly today?
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 00:25

Originally Posted By: Rainwoman_08
I wonder has this system gone through an eye wall replacement already, due to instenfying so rapidly today?
It is very hard to tell. With the eye covered by cloud (the central dense overcast or CDO) the only real way to determine if it has an eye at all is by looking at cloud piercing sensors, such as the microwave sensors like the SSMI or Special Sensor Microwave Imager. Unfortunately these scans are only available when the satellites carrying these sensors (and there are a few) pass overhead. Sometimes they don’t pass directly overhead so we don’t get a good view. In this case, we have essentially only had 3 decent passes since it became a decent storm, so there may have been an ERC in between, but we could not tell! The most recent scan I posted above does not show an eye wall clearly, while the one I posted before hand (at 18:32WST) does ... so it may currently be under going one (as I said in my post above) smile

Hope that makes sense!
Posted by: Dry Tropics

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 00:32

Could someone please indicate at what level (200-850)the sub tropical ridge would be guiding steering, or is that what is even steering the system. CMC and GFS have a Burdekin crossing while EC and NOGAPS have it as a Tully crossing
http://www.weatheronline.co.uk/cgi-bin/e...=0&PERIOD=&WMO=
Where can the difference in steering be identified (don't quite understand what i am looking at) as i am keen to try and understand whay the different model have the different projected paths. Also, what has changed in the past 6 hours to move the xing point higher (and where can i see that. I am more concerned if it begins to drop. Hope all this makes sense.
DT
Posted by: CaptainEd

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 00:33

JTWC # 4

REMARKS:
311500Z POSITION NEAR 13.5S 159.5E.
TROPICAL CYCLONE (TC) 11P (YASI), LOCATED APPROXIMATELY 875 NM
EAST-NORTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED WESTWARD AT
19 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE
IMAGERY SHOWS DEEP CONVECTIVE BANDS WRAPPING TIGHTER INTO THE LOW
LEVEL CIRCULATION CENTER, FUELED BY EXCELLENT RADIAL OUTFLOW. THE
CURRENT INTENSITY IS BASED ON A SOLID DVORAK ESTIMATE OF 90 KNOTS
FROM MULTIPLE AGENCIES INCLUDING KNES, PHFO, NFFN, AND PGTW. TC 11P
IS TRACKING ALONG THE NORTHERN PERIPHERY OF A DEEP SUBTROPICAL RIDGE
(STR) POSITIONED TO THE SOUTH. THE SYSTEM IS EXPECTED TO TRACK
WEST- BECOMING SOUTHWESTWARD AS THE STR SHIFTS EASTWARD WITH THE
APPROACH OF A MID-LATITUDE SHORTWAVE TROUGH FROM THE WEST. UPPER
LEVEL ANALYSIS INDICATES THE SYSTEM HAS DEVELOPED A MESOSCALE
ANTICYCLONE ALOFT AND CONTINUES TO TRACK ALONG AN AREA OF LOW
VERTICAL WIND SHEAR. IN VIEW OF THE FAVORABLE ENVIRONMENT, TC YASI
WILL CONTINUE TO INTENSIFY, PEAKING AT 125 KNOTS BY TAU 36. THE
AVAILABLE NUMERICAL GUIDANCE IS IN EXCEPTIONALLY CLOSE AGREEMENT
THROUGHOUT THE FORECAST PERIOD. TC 11P IS FORECAST TO MAKE
LANDFALL JUST SOUTH OF CAIRNS AS A LARGE 100+ KNOT SYSTEM AFTER TAU
48 AND SHOULD DISSIPATE OVER LAND BY TAU 72. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 311200Z IS 23 FEET. NEXT WARNINGS AT 010300Z AND 011500Z.//
Posted by: CaptainEd

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 00:36

Posted by: PVW

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 00:53

11:30pm Update from the BOM CWS page:
A Cyclone WATCH has been declared for coastal and island communities from Cooktown to Yeppoon and inland to between Georgetown and Moranbah.

Severe Tropical Cyclone Yasi has continued to intensify as it tracks westwards. Further intensification is likely as the cyclone finds favourable conditions over the Coral Sea.

At 10:00 pm EST Monday Severe Tropical Cyclone Yasi, Category 3 was estimated to be 1610 kilometres east northeast of Townsville and 1490 kilometres northeast of Mackay moving west at 30 kilometres per hour.

Damaging winds are expected to develop about coastal and island communities between Cooktown and Yeppoon Wednesday morning, and about adjacent inland parts on Wednesday afternoon.




Forecast Time: +48hr
Date/Time EST: 2200 Wed 02 Feb 2011
Lat: 17.5S
Lon: 147.5E
Accuracy: 145nm
Speed: 15 kn
Central Pressure: 932 hPa
Cat: 4
Max Winds: 105 gusting to 145 kn

Those winds must be bordering Category 5?
Posted by: Dry Tropics

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 00:55

IDQ20080
40:2:2:24:16S154E999:11:00
Australian Government Bureau of Meteorology
Queensland


HURRICANE WARNING 092 ISSUED FROM RSMC NADI Jan 31/1312 UTC 2011 UTC.

SEVERE TROPICAL CYCLONE YASI CENTRE 960HPA CATEGORY 3 WAS LOCATED NEAR 13.6
SOUTH 160.6 EAST AT 311200 UTC.
POSITION POOR.
REPEAT POSITION 13.6S 160.6E AT 311200 UTC.
CYCLONE MOVING WEST AT 17 KNOTS. CYCLONE INTENSIFYING.

EXPECT SUSTAINED WINDS OF 80 KNOTS CLOSE TO THE CENTRE INCREASING TO 90 KNOTS IN

THE NEXT 12 HOURS.
EXPECT WINDS OVER 63 KNOTS WITHIN 40 NAUTICAL MILES OF CENTRE
WINDS OVER 47 KNOTS WITHIN 80 NAUTICAL MILES OF CENTRE IN THE SOUTHERN
SEMICIRLCE AND WITHIN 50 NAUTICAL MILES IN THE NORTHERN SEMICIRCLE.
WINDS OVER 33 KNOTS WITHIN 200 NAUTICAL MILES OF CENTRE IN THE
SOUTHERN SEMICIRCLE AND WITHIN 150 NAUTICAL MILES OF CENTRE IN THE
NORTHEAST
QUADRANT AND WITHIN 80 MILES IN THE NORTHWEST QUADRANT.

FORECAST POSITION NEAR 14.1S 157.1E AT 010000 UTC
AND NEAR 14.8S 153.9E AT 011200 UTC.

THIS WARNING CANCELS AND REPLACES WARNING 091.

RE-ISSUED BY THE BUREAU OF METEOROLOGY, BRISBANE.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 01:15

BoM Technical Bulletin update.
Quote:
IDQ20018
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1301 UTC 31/01/2011
Name: Severe Tropical Cyclone Yasi
Identifier: 14U
Data At: 1200 UTC
Latitude: 13.4S
Longitude: 160.6E
Location Accuracy: within 30 nm [55 km]
Movement Towards: west [275 deg]
Speed of Movement: 19 knots [34 km/h]
Maximum 10-Minute Wind: 80 knots [150 km/h]
Maximum 3-Second Wind Gust: 110 knots [205 km/h]
Central Pressure: 963 hPa
Radius of 34-knot winds NE quadrant: 120 nm [220 km]
Radius of 34-knot winds SE quadrant: 140 nm [260 km]
Radius of 34-knot winds SW quadrant: 140 nm [260 km]
Radius of 34-knot winds NW quadrant: 90 nm [165 km]
Radius of 48-knot winds NE quadrant: 50 nm [95 km]
Radius of 48-knot winds SE quadrant: 70 nm [130 km]
Radius of 48-knot winds SW quadrant: 70 nm [130 km]
Radius of 48-knot winds NW quadrant: 40 nm [75 km]
Radius of 64-knot winds: 30 nm [55 km]
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T5.0/5.0/D1.5/24HRS
Pressure of outermost isobar: 1000 hPa
Radius of outermost closed isobar: 180 nm [335 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 01/0000: 13.9S 156.9E: 050 [095]: 090 [165]: 951
+24: 01/1200: 15.0S 153.7E: 080 [150]: 095 [175]: 944
+36: 02/0000: 16.4S 150.5E: 115 [210]: 100 [185]: 939
+48: 02/1200: 17.5S 147.5E: 145 [270]: 105 [195]: 932
+60: 03/0000: 18.8S 144.5E: 195 [355]: 060 [110]: 976
+72: 03/1200: 20.3S 142.1E: 240 [445]: 030 [055]: 997
REMARKS:
Centre embedded within CDG to give DT 5.0. MET 4.5 with PAT 5.0. FT based on DT.
Improved organisation with rapid development during last 6 to 12 hours. Expect
system to continue intensifying within favourable environment of low shear and
good upper outflow.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 31/1900 UTC by Brisbane
TCWC.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 01:43

Originally Posted By: Dry Tropics
Could someone please indicate at what level (200-850)the sub tropical ridge would be guiding steering, or is that what is even steering the system.


Hi DT .. for this system it would be 400 to 500 hPa. The CIMSS site has deep layer mean winds which will do a good job for you .. try 200 to 700 deep layer mean .. http://cimss.ssec.wisc.edu/tropic2/real-...lm6&zoom=&time=
Posted by: wetfnq

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 03:53


WTPS31 PGTW 311500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 11P (YASI) WARNING NR 004//
RMKS/
1. TROPICAL CYCLONE 11P (YASI) WARNING NR 004
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
311200Z --- NEAR 13.4S 160.5E
MOVEMENT PAST SIX HOURS - 275 DEGREES AT 19 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT
095 NM SOUTHEAST QUADRANT
095 NM SOUTHWEST QUADRANT
090 NM NORTHWEST QUADRANT
REPEAT POSIT: 13.4S 160.5E
---
FORECASTS:
12 HRS, VALID AT:
010000Z --- 13.9S 156.7E
MAX SUSTAINED WINDS - 105 KT, GUSTS 130 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT
055 NM SOUTHEAST QUADRANT
055 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT
105 NM SOUTHEAST QUADRANT
105 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 255 DEG/ 17 KTS
---
24 HRS, VALID AT:
011200Z --- 14.9S 153.3E
MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT
115 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
110 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 250 DEG/ 15 KTS
---
36 HRS, VALID AT:
020000Z --- 16.0S 150.4E
MAX SUSTAINED WINDS - 125 KT, GUSTS 150 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT
115 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
110 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 250 DEG/ 16 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
021200Z --- 17.2S 147.3E
MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 090 NM NORTHEAST QUADRANT
110 NM SOUTHEAST QUADRANT
095 NM SOUTHWEST QUADRANT
090 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 245 DEG/ 14 KTS
---
72 HRS, VALID AT:
031200Z --- 19.3S 141.8E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
311500Z POSITION NEAR 13.5S 159.5E.
TROPICAL CYCLONE (TC) 11P (YASI), LOCATED APPROXIMATELY 875 NM
EAST-NORTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED WESTWARD AT
19 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE
IMAGERY SHOWS DEEP CONVECTIVE BANDS WRAPPING TIGHTER INTO THE LOW
LEVEL CIRCULATION CENTER, FUELED BY EXCELLENT RADIAL OUTFLOW. THE
CURRENT INTENSITY IS BASED ON A SOLID DVORAK ESTIMATE OF 90 KNOTS
FROM MULTIPLE AGENCIES INCLUDING KNES, PHFO, NFFN, AND PGTW. TC 11P
IS TRACKING ALONG THE NORTHERN PERIPHERY OF A DEEP SUBTROPICAL RIDGE
(STR) POSITIONED TO THE SOUTH. THE SYSTEM IS EXPECTED TO TRACK
WEST- BECOMING SOUTHWESTWARD AS THE STR SHIFTS EASTWARD WITH THE
APPROACH OF A MID-LATITUDE SHORTWAVE TROUGH FROM THE WEST. UPPER
LEVEL ANALYSIS INDICATES THE SYSTEM HAS DEVELOPED A MESOSCALE
ANTICYCLONE ALOFT AND CONTINUES TO TRACK ALONG AN AREA OF LOW
VERTICAL WIND SHEAR. IN VIEW OF THE FAVORABLE ENVIRONMENT, TC YASI
WILL CONTINUE TO INTENSIFY, PEAKING AT 125 KNOTS BY TAU 36. THE
AVAILABLE NUMERICAL GUIDANCE IS IN EXCEPTIONALLY CLOSE AGREEMENT
THROUGHOUT THE FORECAST PERIOD. TC 11P IS FORECAST TO MAKE
LANDFALL JUST SOUTH OF CAIRNS AS A LARGE 100+ KNOT SYSTEM AFTER TAU
48 AND SHOULD DISSIPATE OVER LAND BY TAU 72. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 311200Z IS 23 FEET. NEXT WARNINGS AT 010300Z AND 011500Z.//
NNNN

Posted by: wetfnq

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 03:57

Posted by: MareebaWeather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 05:52

I've dedicated one of my scanner feeds to Marine and SES.
Cairns Bureau of Meteorology broadcast at the following times: 5.45am 7.45am 9.45am 11.45am 13.45pm 15.45pm 17.45pm

http://www.radioreference.com/apps/audio/?feedId=6352

----------------------
Mareeba - Queensland - Australia
Live Weather Data & Lightning Tracker
Posted by: mattincairns

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 06:05

IDQP0005
Australian Government Bureau of Meteorology
Queensland
Tropical Cyclone Warning Centre



TOP PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 4
Issued by the Bureau of Meteorology, Brisbane
Issued at 5:02am EST on Tuesday the 1st of February 2011

A Cyclone WATCH is current for coastal and island communities from Cooktown to
Yeppoon, and adjacent inland areas.

A Cyclone WATCH has been declared for Cape Melville to Cooktown, and adjacent
inland areas east of Richmond.

At 4:00 am EST Severe Tropical Cyclone Yasi, Category 3 was estimated to be
1390 kilometres east northeast of Townsville and 1290 kilometres northeast of
Mackay moving west at 30 kilometres per hour.

The cyclone is expected to continue intensifying as it moves west over the Coral
Sea.

Damaging winds are expected to develop about coastal and island communities
between Cape Melville and Yeppoon Wednesday morning, extending to adjacent
inland parts east of Richmond on Wednesday afternoon.

People between Cape Melville and Yeppoon, and adjacent inland parts east of
Richmond should consider what action they will need to take if the cyclone
threat increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 4:00 am EST:
.Centre located near...... 13.6 degrees South 158.4 degrees East
.Location accuracy........ within 65 kilometres
.Recent movement.......... towards the west at 30 kilometres per hour
.Wind gusts near centre... 220 kilometres per hour and INTENSIFYING
.Severity category........ 3
.Central pressure......... 960 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 11:00 am EST Tuesday 01 February.
Posted by: MareebaWeather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 06:49

Coastal Waters Wind Warning
For Cape Melville to Yeppoon
Issued at 5:00 am EST on Tuesday 1 February 2011

Synoptic Situation
Severe Tropical Cyclone Yasi lies over the northern Coral Sea, and is expected to continue intensifying and moving west, impacting upon the central or northeast coast of QLD early on Thursday. This, along with a ridge along the southeast coast of the continent, should cause winds and swells to significantly increase during the week.

Gale Warning
Cape Melville Yeppoon
SW/SE winds increasing to 25/33 knots during Tuesday evening, and increasing further to at least 34/40 knots during Wednesday morning. E/NE swells increasing to 2 to 2.5 metres late on Tuesday, and to at least 4 metres over most waters in the warning area during Wednesday. Swell breaking dangerously in shallow waters from Wednesday.

The next warning will be issued by 11 am AEST.

Please be aware
Wind gusts can be a further 40 percent stronger than the averages given here, and maximum waves may be up to twice the height.
Posted by: Raindammit

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 07:27

TOP PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 4
Issued by the Bureau of Meteorology, Brisbane
Issued at 6:19am EST on Tuesday the 1st of February 2011

** CORRECTED**
A Cyclone WATCH is current for coastal and island communities from Cooktown to
Yeppoon, and adjacent inland areas.

A Cyclone WATCH has been declared for coastal and island communities from Cape
Melville to Cooktown, and adjacent inland areas east of Richmond.

At 4:00 am EST Severe Tropical Cyclone Yasi, Category 3 was estimated to be
1390 kilometres east northeast of Townsville and 1290 kilometres northeast of
Mackay moving west at 40 kilometres per hour.

The cyclone is expected to continue intensifying as it moves west over the Coral
Sea.

Damaging winds are expected to develop about coastal and island communities
between Cape Melville and Yeppoon Wednesday morning, extending to adjacent
inland parts east of Richmond during Wednesday afternoon and evening.

People between Cape Melville and Yeppoon, and adjacent inland parts east of
Richmond should consider what action they will need to take if the cyclone
threat increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 4:00 am EST:
.Centre located near...... 13.6 degrees South 158.4 degrees East
.Location accuracy........ within 65 kilometres
.Recent movement.......... towards the west at 40 kilometres per hour
.Wind gusts near centre... 220 kilometres per hour and INTENSIFYING
.Severity category........ 3
.Central pressure......... 960 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 11:00 am EST Tuesday 01 February.
Posted by: pkgjmg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 08:45

UPPER LEVEL ANALYSIS INDICATES THE SYSTEM HAS DEVELOPED A MESOSCALE ANTICYCLONE ALOFT AND CONTINUES TO TRACK ALONG AN AREA OF LOW VERTICAL WIND SHEAR.

Can someone please explain what this is and what it means for Yasi ?
Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 08:47

IDQ20008
PAN PAN

HIGH SEAS WEATHER WARNING FOR METAREA 10 ISSUED BY THE
AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE BRISBANE
AT 1913UTC 31 JANUARY 2011

HURRICANE FORCE WIND WARNING FOR NORTH EASTERN AREA

SITUATION
At 1800 UTC Severe Tropical Cyclone Yasi was centred within 35 nautical miles of
latitude thirteen decimal six south (13.6S)
longitude one hundred and fifty eight decimal four east (158.4E)
Recent movement : west at 22 knots
Maximum winds : 85 knots
Central pressure: 960 hPa

AREA AFFECTED
Within 220 nautical miles in NE quadrant
and within 300 nautical miles in SE quadrant
and within 300 nautical miles in SW quadrant
and within 160 nautical miles in NW quadrant.

FORECAST
Maximum winds to 85 knots near the centre increasing to 100 knots by 1800 UTC
01 February.

Winds above 64 knots within 70 nautical miles in NE quadrant
and within 100 nautical miles in SE quadrant
and within 90 nautical miles in SW quadrant
and within 30 nautical miles in NW quadrant with phenomenal seas.

Winds above 48 knots within 110 nautical miles in NE quadrant
and within 150 nautical miles in SE quadrant
and within 140 nautical miles in SW quadrant
and within 60 nautical miles in NW quadrant with high to very high seas and
moderate to heavy swell.

Winds above 34 knots within 220 nautical miles in NE quadrant
and within 300 nautical miles in SE quadrant
and within 300 nautical miles in SW quadrant
and within 160 nautical miles in NW quadrant with very rough seas and
moderate to heavy swell.


Forecast positions
At 0600 UTC 01 February: Within 65 nautical miles of 14.3 south 154.9 east
Central pressure 949 hPa.
Winds to 95 knots near centre.
At 1800 UTC 01 February: Within 95 nautical miles of 15.4 south 151.5 east
Central pressure 944 hPa.
Winds to 100 knots near centre.

REMARKS
All ships in the area please send weather reports every three hours. Regular
weather observing ships use normal channels. Other ships please use either
email to marwxqld@bom.gov.au or fax to +61732200221 or satellite to SAC 1241
through Land Earth Station Perth 212.

Next warning will be issued by 0100 UTC 01 February 2011.

WEATHER BRISBANE
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 09:13

An eye seems to be redeveloping in the multi from about 2.5 hours ago but the CDO is still covering it. Some very stron convection appears near the eye on the vis sat shot





Latest BoM Track Map


IDQ20018
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1905 UTC 31/01/2011
Name: Severe Tropical Cyclone Yasi
Identifier: 14U
Data At: 1800 UTC
Latitude: 13.6S
Longitude: 158.4E
Location Accuracy: within 35 nm [65 km]
Movement Towards: west [265 deg]
Speed of Movement: 22 knots [40 km/h]
Maximum 10-Minute Wind: 85 knots [155 km/h]
Maximum 3-Second Wind Gust: 120 knots [220 km/h]
Central Pressure: 960 hPa
Radius of 34-knot winds NE quadrant: 140 nm [260 km]
Radius of 34-knot winds SE quadrant: 180 nm [335 km]
Radius of 34-knot winds SW quadrant: 180 nm [335 km]
Radius of 34-knot winds NW quadrant: 100 nm [185 km]
Radius of 48-knot winds NE quadrant: 60 nm [110 km]
Radius of 48-knot winds SE quadrant: 90 nm [165 km]
Radius of 48-knot winds SW quadrant: 90 nm [165 km]
Radius of 48-knot winds NW quadrant: 50 nm [95 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T5.0/5.0/D1.5/24HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 210 nm [390 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 01/0600: 14.3S 154.9E: 065 [120]: 095 [175]: 949
+24: 01/1800: 15.4S 151.5E: 095 [175]: 100 [185]: 944
+36: 02/0600: 16.4S 148.1E: 130 [235]: 105 [195]: 939
+48: 02/1800: 17.5S 145.2E: 160 [295]: 065 [120]: 976
+60: 03/0600: 18.9S 142.1E: 210 [385]: 035 [065]: 992
+72: 03/1800: 19.8S 139.6E: 255 [470]: 030 [055]: 998
REMARKS:
Centre embedded within White to give DT 5.0. MET 5.0 with PAT 5.0. FT based on
DT. Improved organisation with rapid development during last 6 to 12 hours.
Expect system to continue intensifying within favourable environment of low
shear and good upper outflow.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 01/0100 UTC by Brisbane
TCWC.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 10:10

Originally Posted By: pkgjmg
UPPER LEVEL ANALYSIS INDICATES THE SYSTEM HAS DEVELOPED A MESOSCALE ANTICYCLONE ALOFT AND CONTINUES TO TRACK ALONG AN AREA OF LOW VERTICAL WIND SHEAR.

Can someone please explain what this is and what it means for Yasi ?


Not quite sure why they chose the term "mesoscale anticyclone" - all severe TC's worthy of the name have a upper level high (anticyclone) over the top. Essentially if there is air spiralling in at the bottom and lifting upwards then at the top of the atmosphere the air is forced to spiral outwards.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 10:17

Yasi appears to have struggled a little over night .. with a persistent large central dense overcast.

The 37 mhz suggests there is a small scale feature embedded within the large scale structure right in the eye centre. Once that feature erodes we shold see the eye develop properly this morning. I was going to call a pinhole eye - but the guys I talk to reckon that it will just be a normal eye feature - and they should know.




And now I see OV's post above - sorry!
Posted by: Brett Guy

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 10:18

My guess is that it means that Yasi has developed it's own upper high above it rather than relying on being under a pre-existing upper high. Those that know more please tell me if that is correct.
Posted by: Inclement Weather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 10:18

I thought that curious myself ITN. I think the BoM have nailed the track; however, the intensity is still uncertain. With optimal conditions all the way to the coast: high SSTs; low or no shear; and good outflow; there is still scope for an even higher intensity than the current Cat 4. The only thing I can see that will inhibit intensification or weaken it will be, because of its sheer size, interaction with the land the closer it gets to the coast and the eyewall replacement cycle.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 10:39

Hi Clem .. once the analysis goes Cat 4 the BoM will go Cat 5 in the forecast ..

However the ocean heat content for this system is down a little so it may struggle to get to or maintain a Cat 5 (which is good news). One thing is that it is moving relatively quickly so upwelling cold water may not be as big an issue. Certainly it is moving into less favourable ocean regime.

Posted by: synopig

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 10:47

This is an interesting site from the CSIRO, point and click. Showing a 28 deg+ SST all the way to the coast.

http://www.marine.csiro.au/~lband/web_point/
Posted by: Tempest

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 11:30

South west quadrant now seems to be more enhanced, which tells me upper levels (ridiging)have relaxed, would not be surprised to see a s.w movemnt soon.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 11:34

Partial eye visible on visible

Posted by: Rocky Raccoon

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 11:47

I have just had a look at its predicted path and if they are correct it will be just 100 kilometers off the coast from Cairns when the tide peaks at 2.8 meters at 9.30 AM. How would this go for issues of storm surges?
Posted by: Rocky Raccoon

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 12:03


Image from this source

Here is the CSIRO sea surface temperature. It just looks kind of "warmish" in the Coral Sea but much warmer off North Western Australia.
Posted by: Scottie A

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 12:04

Just a little more layman info/explanation here I also posted in the general thread

The latest MTSAT could be showing a turn the WSW-SW by Yasi this would coincide with the upper low starting its track to the south west - South as ive mentioned, which is caused by the high near NZ finally moving far enough East relaxing the ridge along the QLD coast therefore allowing Yasi and the upper low to starting dipping in more of a Southerly direction. Will need a few more frames to confirm though, also as others have mentioned yasi is starting to open up a nice eye, which will make tracking much easier
Posted by: Meebo

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 12:11

IDQP0005
Australian Government Bureau of Meteorology
Queensland
Tropical Cyclone Warning Centre

Media: The Standard Emergency Warning Signal should NOT be used with this
warning.

TOP PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 5
Issued by the Bureau of Meteorology, Brisbane
Issued at 11:09am EST on Tuesday the 1st of February 2011

A Cyclone WARNING has been declared for coastal areas from Cooktown to Sarina.

A Cyclone WATCH has been declared for coastal areas from Lockhart River to
Cooktown and Sarina to Yeppoon and for southern Cape York Peninsula and inland
areas north of Charters Towers.

At 10:00 am EST Severe Tropical Cyclone Yasi, Category 3 was estimated to be
1220 kilometres east northeast of Cairns and 1200 kilometres east northeast of
Townsville
moving west at 35 kilometres per hour.

The cyclone is expected to continue intensifying as it moves west over the Coral
Sea.

SEVERE TROPICAL CYCLONE YASI, CATEGORY 3, with gusts up to 220 km/h is currently
moving in a westerly direction at 35km/hr but is expected to turn on a more
west-southwesterly direction in the next 12 hours.

DAMAGING winds with gusts to 100km/hr are expected to develop on the islands
during Wednesday morning and extend onto the coast during the day and extend
inland across southern Cape York Peninsula and north of Charters Towers
overnight Wednesday.

These winds will become DESTRUCTIVE with gusts in excess of 125km/hr about the
coast and islands late Wednesday between Cooktown and Townsville.


People between Cooktown and Sarina should immediately commence or continue
preparations, especially securing boats and property [using available daylight
hours/before nightfall].
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

People between Lockhart River and Cooktown and between Sarina and Yeppoon, and
southern Cape York Peninsula and inland north of Charters Towers should consider
what action they will need to take if the cyclone threat increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 10:00 am EST:
.Centre located near...... 14.0 degrees South 156.7 degrees East
.Location accuracy........ within 55 kilometres
.Recent movement.......... towards the west at 35 kilometres per hour
.Wind gusts near centre... 220 kilometres per hour and INTENSIFYING
.Severity category........ 3
.Central pressure......... 960 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 2:00 pm EST Tuesday 01 February.

This warning is also available through TV and Radio Broadcasts; the Bureau's
website at www.bom.gov.au or call 1300 659 212. The Bureau and the State
Emergency Service would appreciate this warning being broadcast regularly.
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 12:14

Originally Posted By: Scottie A
Just a little more layman info/explanation here I also posted in the general thread

The latest MTSAT could be showing a turn the WSW-SW by Yasi this would coincide with the upper low starting its track to the south west - South as ive mentioned, which is caused by the high near NZ finally moving far enough East relaxing the ridge along the QLD coast therefore allowing Yasi and the upper low to starting dipping in more of a Southerly direction. Will need a few more frames to confirm though, also as others have mentioned yasi is starting to open up a nice eye, which will make tracking much easier


lol i was just about to start on this subject Scotty. Heres the steering winds as of now from CIMSS.
High looks to have tilted quite a lot?

[img:left][/img]
Posted by: Meebo

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 12:14

Remarks:

SEVERE TROPICAL CYCLONE YASI, CATEGORY 3, with gusts up to 220 km/h is currently moving in a westerly direction at 35km/hr but is expected to turn on a more west-southwesterly direction in the next 12 hours.

DAMAGING winds with gusts to 100km/hr are expected to develop on the islands during Wednesday morning and extend onto the coast during the day and extend inland across southern Cape York Peninsula and north of Charters Towers overnight Wednesday.

These winds will become DESTRUCTIVE with gusts in excess of 125km/hr about the coast and islands late Wednesday between Cooktown and Townsville.


People between Cooktown and Sarina should immediately commence or continue preparations, especially securing boats and property [using available daylight hours/before nightfall].
- For cyclone preparedness and safety advice, visit Queensland's Disaster Management Services website (www.disaster.qld.gov.au)
- For emergency assistance call the Queensland State Emergency Service (SES) on 132 500 (for assistance with storm damage, rising flood water, fallen trees on buildings or roof damage).

People between Lockhart River and Cooktown and between Sarina and Yeppoon, and southern Cape York Peninsula and inland north of Charters Towers should consider what action they will need to take if the cyclone threat increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster Management Services website (www.disaster.qld.gov.au)
- For emergency assistance call the Queensland State Emergency Service (SES) on 132 500 (for assistance with storm damage, rising flood water, fallen trees on buildings or roof damage).

Name: Severe Tropical Cyclone Yasi

Details:
Time (EST) Intensity Category Latitude
(decimal deg.) Longitude
(decimal deg.) Estimated Position
Accuracy (km)
0hr 10 am February 1 3 14.0S 156.7E 55
+6hr 4 pm February 1 3 14.3S 154.8E 85
+12hr 10 pm February 1 4 14.6S 153.0E 95
+18hr 4 am February 2 4 15.2S 151.3E 120
+24hr 10 am February 2 4 15.8S 149.6E 150
+36hr 10 pm February 2 4 16.7S 146.0E 205
+48hr 10 am February 3 1 18.0S 142.7E 240


The next Forecast Track Map will be issued by 2:00 pm EST Tuesday
Posted by: Inclement Weather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 12:29

TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 0123 UTC 01/02/2011
Name: Severe Tropical Cyclone Yasi
Identifier: 14U
Data At: 0000 UTC
Latitude: 14.0S
Longitude: 156.7E
Location Accuracy: within 30 nm [55 km]
Movement Towards: west [259 deg]
Speed of Movement: 18 knots [33 km/h]
Maximum 10-Minute Wind: 85 knots [155 km/h]
Maximum 3-Second Wind Gust: 120 knots [220 km/h]
Central Pressure: 960 hPa
Radius of 34-knot winds NE quadrant: 140 nm [260 km]
Radius of 34-knot winds SE quadrant: 200 nm [370 km]
Radius of 34-knot winds SW quadrant: 200 nm [370 km]
Radius of 34-knot winds NW quadrant: 110 nm [205 km]
Radius of 48-knot winds NE quadrant: 50 nm [95 km]
Radius of 48-knot winds SE quadrant: 70 nm [130 km]
Radius of 48-knot winds SW quadrant: 70 nm [130 km]
Radius of 48-knot winds NW quadrant: 50 nm [95 km]
Radius of 64-knot winds: 30 nm [55 km]
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T5.0/5.0/D1.5/24HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 210 nm [390 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 01/1200: 14.6S 153.0E: 050 [095]: 090 [165]: 950
+24: 02/0000: 15.8S 149.6E: 080 [150]: 100 [185]: 944
+36: 02/1200: 16.7S 146.0E: 110 [205]: 105 [195]: 938
+48: 03/0000: 18.0S 142.7E: 130 [240]: 045 [085]: 987
+60: 03/1200: 19.2S 140.0E: 160 [295]: 030 [055]: 999
+72: 04/0000: 20.5S 137.4E: 190 [350]: 025 [045]: 1002
REMARKS:
Yasi continues to develop assisted by a environment of low shear, good upper
level outflow and high ocean heat content [SST]. Dvorak based on ongoing
embedded centre in white to give DT 5.0 although adjusted MET and visibile
analysis indicates 4.5. FT/CI maintained at 5.0. Mean winds estimated at 85
knots [top end 5.0] supported by SATCON [95 knots 1min mean] as CIMMS AMSU
estimates are higher than ADT.

Further intensification can be expected with low shear, upper outflow
environment persisting until landfall. SSTs are slightly lower on the forecast
track to about 28C but this may not be a sufficient to inhibit intensification.

Forecast motion is steady to the west with a persisting mid-level ridge to the
south. Models are quite consistent with the forecast motion which may become a
little more WSW in 12-18 hours possibly assisted by some beta affect.

The combined factors of being intense, large, and motion at 18 knots are
conducive for greater wave/swell generation to the south of of the forecast
track.

With the expectation of being a large and intense system, cyclone intensity may
be maintained further inland than normal.


As previously discussed in bold.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 12:30

Originally Posted By: He who once was ITN
Partial eye visible on visible




Yep much more clear now


A little surprised this didnt happen earlier.
Posted by: Cliffhanger

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 12:51

opplevelse, where do i get that link plz
www.nrlmry.navy.mil/sat_products.html where then?
Posted by: floody

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 13:08

The timing of the cyclone in regards to tides will be critical. On the high tide the chance of storm surge induced flooding is much greater. The slowing of Yasi seems to bring the crossing to mid-tide, but at least after 9pm it will be falling.

Here is the link to the BoM tide site: Queensland Tides

You can select the location you want the tides for from this interface.
Posted by: lou lou

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 13:38

Not sure if this helps anyone with tides


Briefing Note
February 1 2011
RE: CENTRAL HIGHLANDS AND TROPICAL CYCLONE YASI
The Central Highlands Regional Council Mayor, Councillor Peter Maguire, issued the
following statement this morning.
The Mayor, CEO and Council’s Disaster Manager participated in a State Disaster
Coordination Centre teleconference at 8am this morning.
The following details were provided in relation to TC Yasi:
• It is currently a very large powerful Category 3 cyclone and expected to reach a
high Category 4.
• The track has changed to cross the coast between Cairns and Innisfail
• The system is moving west at a high speed of 40kph and is expected to then
change to WSW (most cyclones move at about 25kph)
• Gale force winds are expected from Cooktown to Mackay with the area from
Mossman to Ayr/Home Hill being the focus area for storm force winds. (Mackay
could still receive Category 1 winds).
Estimated to cross landfall at 1am on Thursday morning at low tide.
•Councils, EMQ, BOM and other state departments have prepared storm surge
maps for the effected areas and will be on their respective websites.
• We should have a much clearer picture at 10am tomorrow morning after the
system passes the Willis Island radar.
• The rainfall area is expected to pass the Northern Goldfields and northern areas
including Richmond and Mt Isa.
• Rainfall for the Central Highlands area is now expected to be substantially
reduced with the heaviest rain north of Clermont and in the Belyando River
catchment. Other than normal isolated storms it is estimated the areas south of
Clermont may receive in the 10-20mm range. On current information for this
system the risk of further flooding in the Central Highlands is low.
• Winds Wednesday night to Thursday night could be up to 40-60 kph. This is a
strong wind so residents in the Central Highlands need to secure loose items and
check temporary structures such as awnings.
It is still important to keep a watching brief and be on standby as cyclones have been
known to change direction. Council will continue to monitor this cyclone and provide
updates through this event.
A further briefing for Central Highlands residents will be provided tomorrow, February 2
2011.
Residents are reminded that Council continues to operate a Recovery Centre from the
corner of Campbellford Drive and the Gregory Highway, and in parthership with other
agencies will provide ongoing support and information for residents affected by the
recent flood event.
Councillor Peter Maguire
Mayor, Central Highlands Regional Council
Chair Central Highlands Local Disaster Management Group
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 13:41

According to the microwave image, the eye "proper" is further south than what is depicted above.

Can anybody see the cloud forming to the East of SEQ on the sat pic? That is coming from the upper low that is squashing the ridge down and to the east. With that cloud now starting to grow towards Yazi, does this now show that the steering winds have changed and is basically reaching out to Yazi to pull her down?
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 13:44

I am so confused by the BOM.

If it headed WSW from now it would hit between townsville and Cardwell, if it moved WSW in the next 6 hours, it would move towards inhgam - cardwell.


Okay so the latest model runs are
CMC - Ingham too cardwell crossing
EC - Cardwell Crossing
GFS - Ingham to cardwell

What am i missing????? I think they have put it over cairns too alert the city, i dont think cairns will get nailed. The models are showing alot of consistancy, and they are the best we have
Posted by: H'Bay Qld

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 13:49

Poncho, the other day you were talking about the possibility of Yasi, if strong enough and the ridge was weak enough that she could come further south???
Posted by: Brett Guy

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 13:50

JTWC just updated. They are showing Innisfail crossing
http://www.usno.navy.mil/NOOC/nmfc-ph/RSS/jtwc/warnings/sh1111.gif
Posted by: Scottie A

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 13:51

Originally Posted By: Trav Dog
I am so confused by the BOM.

If it headed WSW from now it would hit between townsville and Cardwell, if it moved WSW in the next 6 hours, it would move towards inhgam - cardwell.


Okay so the latest model runs are
CMC - Ingham too cardwell crossing
EC - Cardwell Crossing
GFS - Ingham to cardwell

What am i missing????? I think they have put it over cairns too alert the city, i dont think cairns will get nailed. The models are showing alot of consistancy, and they are the best we have


Trav I think the BOM are going by ACCESS A/T which is silly because with Anthony these models forecasted a crossing much further north (overestimate ridging) and got it wrong, with all likelyhood will do the same this time!! We are best sticking with EC seems to have done a rather brilliant job of the last system and so far has been great with this one (Yasi) aswell.
Posted by: Unsettled

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 13:54

Originally Posted By: Trav Dog
I am so confused by the BOM.

If it headed WSW from now it would hit between townsville and Cardwell, if it moved WSW in the next 6 hours, it would move towards inhgam - cardwell.


Okay so the latest model runs are
CMC - Ingham too cardwell crossing
EC - Cardwell Crossing
GFS - Ingham to cardwell

What am i missing????? I think they have put it over cairns too alert the city, i dont think cairns will get nailed. The models are showing alot of consistancy, and they are the best we have


Trav - as I posted the other night while you were off chasing Tony wink

The directions given by the BoM are necessarily generalistic. The difference between W & WSW is 22.5deg, which is a big spread over 1000-1500kms. Don't get too caught up with thinking that a system is going to travel at bearing x degrees and y minutes. smile
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 13:55

Originally Posted By: Scottie A
Originally Posted By: Trav Dog
I am so confused by the BOM.

If it headed WSW from now it would hit between townsville and Cardwell, if it moved WSW in the next 6 hours, it would move towards inhgam - cardwell.


Okay so the latest model runs are
CMC - Ingham too cardwell crossing
EC - Cardwell Crossing
GFS - Ingham to cardwell

What am i missing????? I think they have put it over cairns too alert the city, i dont think cairns will get nailed. The models are showing alot of consistancy, and they are the best we have


Trav I think the BOM are going by ACCESS A/T which is silly because with Anthony these models forecasted a crossing much further north (overestimate ridging) and got it wrong, with all likelyhood will do the same this time!! We are best sticking with EC seems to have done a rather brilliant job of the last system and so far has been great with this one (Yasi) aswell.


EC had it just south of Cairns lastnight though, while CMC and GFS had it further south near Tville.
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 14:00

Originally Posted By: H'Bay Qld
Poncho, the other day you were talking about the possibility of Yasi, if strong enough and the ridge was weak enough that she could come further south???


Yeah the BOM did actually mention something about the "beta effect" coming in to play as a possibility.

It was this scenario that i posted earlier....seems to be coming off?

Originally Posted By: TC Poncho
Originally Posted By: Popeye
My undersatnding also is that intense systems are steered high in the uppers whereas Smaller CAT1+2s are steered closer to the surface. Can anyone see any insights into what Upper atmosphere systems will come into play that might give a little shift here or there or is it going to be straightine Steering WSW to the coast.


GFS +12hrs, that low to the right of SEQ is set to take over and head E into the over SEQ, hence South steering!


GFS +24hrs


GFS +36hrs
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 14:09

Also for consideration, ex TC Anthony...look how far south he is now! I heard that met guy off "western pacific weather" say on his webcast that Yazi will tend to go towards the nearest low pressure source.
Posted by: Brett Guy

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 14:24

As per a couple of posts back JTWC are progging landfall around the cairns/innisfail area and this is the vis loop with predicted path
http://www.ssd.noaa.gov/mtsat/flt/t1/loop-vis.html
Posted by: pkgjmg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 14:51

i have a question and hoping 1 of you guys can answer it for me smile .. I am just learning so please bare with me, if I'm wrong that's ok - you can tell me with no offence taken smile

looking at the MTSAT water vapour loop - upper low's spin clockwise right ? .. so IS there 2 upper low's below Yasi - and if so what effect are they going to have on her steering ?

also off topic a bit - but is there another low at 170degE, 20degS forming ?
Posted by: cyclonecece

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 14:53

IDQP0005
Australian Government Bureau of Meteorology
Queensland
Tropical Cyclone Warning Centre

Media: The Standard Emergency Warning Signal should NOT be used with this
warning.

TOP PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 6
Issued by the Bureau of Meteorology, Brisbane
Issued at 1:52pm EST on Tuesday the 1st of February 2011

A Cyclone WARNING is current for coastal areas from Cooktown to Sarina.

A Cyclone WATCH is current for coastal areas from Lockhart River to Cooktown and
Sarina to Yeppoon and for the northern tropical interior.

At 1:00 pm EST Severe Tropical Cyclone Yasi, Category 3 was estimated to be
1120 kilometres east northeast of Cairns and 1110 kilometres east northeast of
Townsville
moving west at 34 kilometres per hour.

YASI IS A LARGE AND POWERFUL TROPICAL CYCLONE AND POSES A SERIOUS THREAT TO
NORTH QUEENSLAND COMMUNITIES

The cyclone is expected to slowly intensify overnight as it moves westwards over
the Coral Sea.

SEVERE TROPICAL CYCLONE YASI, CATEGORY 3 is expected to turn on a more
west-southwesterly direction in the next 12 hours.

DAMAGING winds with gusts to 90 km/hr are expected to develop on the islands
during Wednesday morning, then extend onto the coast during the day, and further
inland across southern Cape York Peninsula and north of Charters Towers
overnight.

Between Cooktown and Townsville these winds will become DESTRUCTIVE with gusts
in excess of 125km/hr late Wednesday afternoon.

As the centre approaches the coast sea levels will rise above the normal tide
with damaging waves and flooding of low lying areas near the shoreline.

Flooding rains will develop from Cooktown to Sarina during Wednesday afternoon
and then extend inland overnight.


People between Cooktown and Sarina should immediately commence or continue
preparations, especially securing boats and property [using available daylight
hours/before nightfall].
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

People between Lockhart River and Cooktown and between Sarina and Yeppoon, and
southern Cape York Peninsula and inland north of Charters Towers should consider
what action they will need to take if the cyclone threat increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 1:00 pm EST:
.Centre located near...... 14.2 degrees South 155.8 degrees East
.Location accuracy........ within 55 kilometres
.Recent movement.......... towards the west at 34 kilometres per hour
.Wind gusts near centre... 220 kilometres per hour and INTENSIFYING
.Severity category........ 3
.Central pressure......... 960 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 5:00 pm EST Tuesday 01 February.

This warning is also available through TV and Radio Broadcasts; the Bureau's
website at www.bom.gov.au or call 1300 659 212. The Bureau and the State
Emergency Service would appreciate this warning being broadcast regularly.
Posted by: CivEngSean

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 14:55

I just posted this in the Chat thread and thought it deserves to be here.

I just did a quick search through my codes... These are the winds speeds buildings are designed to now.

from AS1170.2
if your above Bundy and on the coast the design winds are:
V50-52m/s
V100-56m/s
V500-66m/s
V1000-70m/s

These will change depending on how exposed your house is, your elevation, shape of your house and its angle.

The V1000 wind speed is 250km/h so most houses are NOT designed to this.
Posted by: Maisie

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:05

Centre Located at 10am 14.0s 156.7e
Centre Located at 2pm 14.2s 155.8e
Posted by: floody

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:08

The latest track map is of great concern regards storm surge, showing a crossing at Cairns on or near the high tide tomorrow night. As a geomorphologist I'm quite concerned about the effects of storm surge - I remember doing my Masters degree and looking at the storm surge that affected Mackay and the effects of storm surge and large waves are VERY serious.
At high tide in Cairns how many metres between the normal tide level and land level?
Posted by: bunyaglen

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:16

Originally Posted By: floody
The latest track map is of great concern regards storm surge, showing a crossing at Cairns on or near the high tide tomorrow night. As a geomorphologist I'm quite concerned about the effects of storm surge - I remember doing my Masters degree and looking at the storm surge that affected Mackay and the effects of storm surge and large waves are VERY serious.
At high tide in Cairns how many metres between the normal tide level and land level?


Sea level on the Cairns foreshore (at high tide) is only a matter of a few metres (at most) below the entire city area.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:17

Floody your comments are in conflict with the statement issued before (as noted by Lou Lou). Have you got any references for your claim it will in fact be high tide at crossing?

Originally Posted By: lou lou
Not sure if this helps anyone with tides
Briefing Note
February 1 2011
RE: CENTRAL HIGHLANDS AND TROPICAL CYCLONE YASI
The Central Highlands Regional Council Mayor, Councillor Peter Maguire, issued the
following statement this morning....

Estimated to cross landfall at 1am on Thursday morning at low tide.
•Councils, EMQ, BOM and other state departments have prepared storm surge
maps for the effected areas and will be on their respective websites....
Posted by: Greg Sorenson

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:19

Thought i'd post this here regarding house design criteria's in TC regions. I work in the building industry and have to get things through council, albeit in non-Tc regions, however the same theory applies to higher wind potential locations. Many older homes of course wont be up to this standard, but i hope it gives a better understanding of how racking and suction forces apply to buildings.

http://www.nt.gov.au/lands/building/cyclones/documents/CTSCyclPres.pdf
Posted by: ColdFront

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:20

Originally Posted By: opplevelse
Floody your comments are in conflict with the statement issued before (as noted by Lou Lou). Have you got any references for your claim it will in fact be high tide at crossing?

Originally Posted By: lou lou
Not sure if this helps anyone with tides
Briefing Note
February 1 2011
RE: CENTRAL HIGHLANDS AND TROPICAL CYCLONE YASI
The Central Highlands Regional Council Mayor, Councillor Peter Maguire, issued the
following statement this morning....

Estimated to cross landfall at 1am on Thursday morning at low tide.
•Councils, EMQ, BOM and other state departments have prepared storm surge
maps for the effected areas and will be on their respective websites....

Correct. 1am is actually at low tide. If course being so far from the coast it may slow down or speed up and affect that outcome but at this stage (particularly with the reef where it is) storm surge is not my greatest concern. With a system this size and projected rainfall the Barron River flood plain may beocme the inland sea it was in the 50's and that is bad news for tanywhere between Smithfield and the airport.
Posted by: Greg Sorenson

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:23

Originally Posted By: pkgjmg
i have a question and hoping 1 of you guys can answer it for me smile .. I am just learning so please bare with me, if I'm wrong that's ok - you can tell me with no offence taken smile

looking at the MTSAT water vapour loop - upper low's spin clockwise right ? .. so IS there 2 upper low's below Yasi - and if so what effect are they going to have on her steering ?

also off topic a bit - but is there another low at 170degE, 20degS forming ?


Yes in the southern Hem lows always circulate clockwise. It's hard to say regarding the other lows, but i would suggest it will be the high pressure ridge that be the final deciding factor of how far sw, (if at all) Yasi will go.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:25

JTWC warning #5 has increased intensity to sustained 125 and gusts to 150kts that is Category 5 territory at crossing. Also further north


Posted by: Learjet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:26

NOAA 19 pass at 2pm received from Andergrove (Mackay).

Would have been nice for the pass to be more easterly but you can't pick and choose with polar orbiters.

Anyway, a ROUGH estimate puts the eye at 1022km and 44 degrees from my location at Andergrove.

Posted by: Greg Sorenson

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:29

Originally Posted By: ColdFront
Originally Posted By: opplevelse
Floody your comments are in conflict with the statement issued before (as noted by Lou Lou). Have you got any references for your claim it will in fact be high tide at crossing?

Originally Posted By: lou lou
Not sure if this helps anyone with tides
Briefing Note
February 1 2011
RE: CENTRAL HIGHLANDS AND TROPICAL CYCLONE YASI
The Central Highlands Regional Council Mayor, Councillor Peter Maguire, issued the
following statement this morning....

Estimated to cross landfall at 1am on Thursday morning at low tide.
•Councils, EMQ, BOM and other state departments have prepared storm surge
maps for the effected areas and will be on their respective websites....

Correct. 1am is actually at low tide. If course being so far from the coast it may slow down or speed up and affect that outcome but at this stage (particularly with the reef where it is) storm surge is not my greatest concern. With a system this size and projected rainfall the Barron River flood plain may beocme the inland sea it was in the 50's and that is bad news for tanywhere between Smithfield and the airport.


Spot on CF. yes storm surge will be of concern to those right on the water front and perhaps a few streets back, but the intense rainfall over already saturated ground could potentially make the Barron (and other river and creek systems) burst their banks, simply due to the huge volume of rainfall. The flood inundation maps for cairns (see link below) show that many areas, ie my parents home in Manunda, could be in strife. As i type this, my parents are currently collecting sandbags after our discussion last night on skype.

http://www.police.qld.gov.au/forms/qldfloods/cairns.html
Posted by: avinet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:29

Originally Posted By: Maisie
Centre Located at 10am 14.0s 156.7e
Centre Located at 2pm 14.2s 155.8e


That gives a 4 hour travel distance of 100km on a bearing of 257, only 25 km/hr

Cairns is 1140 km away at the same 257 bearing from its 2pm position
Posted by: Scottie A

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:30

Originally Posted By: pkgjmg
i have a question and hoping 1 of you guys can answer it for me smile .. I am just learning so please bare with me, if I'm wrong that's ok - you can tell me with no offence taken smile

looking at the MTSAT water vapour loop - upper low's spin clockwise right ? .. so IS there 2 upper low's below Yasi - and if so what effect are they going to have on her steering ?

also off topic a bit - but is there another low at 170degE, 20degS forming ?


Ok here we go Pkgjmg, you got some good eyes there... Yes there are three upper lows present atm showing on the MTSAT WV loop. Ive numbered and marked the path of travel so hopefully this will make explaining much more easier and clearer.

Number 1 which is just grazing the SEQ coast will get thrown around the outside of the high pressure system which is currently sitting near NZ moving and extending a ridge up the QLD coast stopping Yasi from barreling down the coast but however with this high moving slightly to the east, the ridge up the Qld coastline will weaken slightly allowing for Yasi to slip in a WSW to mabye SW direction dependent on how far east this high pressure system pushes weakening the QLD ridge.

Number 2 is heading in a NW direction, either 3 will completely die out over the next 6-12hrs or possibly merge with 2 once either of these situations have taken place this upper low will then head NW towards Vanuatu giving Yasi a good shove towards the coast and inhibiting any further development for a while over the Coral sea behind Yasi.



I hope I havent left anything out and this has answered your question...
Posted by: avinet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:37

Relevant tide times for Cairns from the BOM site

Wednesday high tide at 20.53 at 2.38 metres

Thursday low tide at 0300 at 0.54 metres
high tide at 0939 at 2.96 metres.

Better hope it arrives with the low tide and isn't delayed a few hours until 9am
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:47

Originally Posted By: avinet
Relevant tide times for Cairns from the BOM site

Wednesday high tide at 20.53 at 2.38 metres

Thursday low tide at 0300 at 0.54 metres
high tide at 0939 at 2.96 metres.

Better hope it arrives with the low tide and isn't delayed a few hours until 9am


Thanks I assume they are local QLD times?. JTWC have Yasi crossing at ~12-13:00Z or 10-11pm AEST (QLD time), which puts it at a reducing tide, but still pretty close to high tide. The BoM has it tracking slightly slower with a crossing time of 14:00-15:00Z or 12-1am, so it will be half way between high and low tide at cairns then.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 15:55

There should be a good Microwave image from TMI onboard TRMM soon, over pass time was 1hr ago. It will be interesting to see how wellformed that eye is, as it is a little hard to tell from the vis and IR shots (which are the only thing we have had in the last 6 hrs!!)
Posted by: Raindammit

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 16:21

Latest (3:00pm) forecast by GFS:

Posted by: camtsv

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 16:24

hey guys, been off here for an hour or so, but its definatly gone to the WSW. Abit earlier than the within the next 12 hours like BOM have said on there bulletins.

Thoughts????
Posted by: explorer

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 16:24

Thank you Scottie A for this post, very clear answer. I had been wondering about this since yesterday, even posting a couple of questions (the 'ice cream blob' thingy) but did not get a direct answer until your post. Thank you for taking the time to explain these formations in lay terms ...

Originally Posted By: Scottie A
Originally Posted By: pkgjmg
i have a question and hoping 1 of you guys can answer it for me smile .. I am just learning so please bare with me, if I'm wrong that's ok - you can tell me with no offence taken smile

looking at the MTSAT water vapour loop - upper low's spin clockwise right ? .. so IS there 2 upper low's below Yasi - and if so what effect are they going to have on her steering ?

also off topic a bit - but is there another low at 170degE, 20degS forming ?


Ok here we go Pkgjmg, you got some good eyes there... Yes there are three upper lows present atm showing on the MTSAT WV loop. Ive numbered and marked the path of travel so hopefully this will make explaining much more easier and clearer.

Number 1 which is just grazing the SEQ coast will get thrown around the outside of the high pressure system which is currently sitting near NZ moving and extending a ridge up the QLD coast stopping Yasi from barreling down the coast but however with this high moving slightly to the east, the ridge up the Qld coastline will weaken slightly allowing for Yasi to slip in a WSW to mabye SW direction dependent on how far east this high pressure system pushes weakening the QLD ridge.

Number 2 is heading in a NW direction, either 3 will completely die out over the next 6-12hrs or possibly merge with 2 once either of these situations have taken place this upper low will then head NW towards Vanuatu giving Yasi a good shove towards the coast and inhibiting any further development for a while over the Coral sea behind Yasi.



I hope I havent left anything out and this has answered your question...
Posted by: floody

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 16:28

Hi Greg, tide estimate based on the revised track map from the BoM - on the latest track map by 1am its already well inland near Atherton, That gives a crossing time to me close to 10-11pm and not far off the high tide. As later noted agreed by JTWC. Lou's post was of a media announcement using the old BoM data from the track map before last.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 16:37

Grrr Aqua was just teasing, just missed the eye! Still waiting on TMI

Posted by: bazookabob

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 16:48

Hi guys - was going to post this on the chat forum but im hoping i might get a better response here. Just a question regarding the GFS model from the mid January period for those of you who have been tracking TCY for a long period now. Was TCY shown on the long range forecast and if so, what was the accuracy of the earlier models compared to it's current track and intensity?

Thanks smile
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 16:58

Baz, they predicted it pretty musch spot on. But this was not a particullarly hard cyclone to "predict". It is under the influence of relatively stron steering influences and excellent formation conditions, so any tom dick or harry could have told you once the low formed that it would be big and where it would hit ... they are not all this easy unfortunately.
Posted by: RWM's Daughter

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 17:04

Bazookabob I don't know about the GFS model specifically, but yes Yasi was in the models however they were all over the place with their forecast crossing points - some even suggested a SEQ crossing which caused all that media hype.

However re the intensity, they were all pretty accurate with that from memory.

Someone else should be able to answer more specifically about the GFS model.

Hope this helps a bit anyway.
Posted by: max power

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 17:06

Looking at the current Mstat (http://www.goes.noaa.gov/sohemi/sohemiloops/shirgmscol.html) its showing TCY take a more southerly direction than forcasted on the current track map. Atm we are seeing the eye at pretty much 15S 155E, which is easily a further 1 degree than anticipated on the track map in the space of 4 hours. I really wonder how much emphasis the two highs will have on its southerly track later into this evening and tomorrow morning. If it continues on the track as shown in the lastest MSTAT, i think will will see a crossing between Townsville and Bowen.
Posted by: Brett Guy

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 17:11

It is not heading in the direction you think. MTSAT images can be quite deceptive.ATM it is still heading at roughly 260deg which is just south of west.
Posted by: LightningBoltz

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 17:11

Wow willis Island radar is starting to show the outer bands and there pressure has dropped from 1008.3 to 1003.8 since 9am wind gusts are starting to pickup 52km at 3.30pm looks like a lot of rain even in the outer bands http://www.bom.gov.au/products/IDR411.loop.shtml#skip
Posted by: Thunderstruck

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 17:25

Another reminder to all posters that this thread is strictly for technical discussion only. If you have anything else not related to technical discussion, please post it in the general chat thread.

TS cool
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 17:28

Latest MW data from TRMM ... finally! Next one from SSMIS in an hour or two


Eye not as solid as I thought it would be, but still looking a lot better than before. Overall structure is considerably improved, but still has a way to go.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 17:51

Sorry I should clarify that by "better" I mean better from a storm structure point of view ... i.e. the structure of Yasi is improving, becoming more symmetrical(as to be expected for a strengthening cyclone) ... it is not "better" from QLD's point of view.
Posted by: Rhubarb

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 17:54

Posted this on general chat but thought you guys might be intersted.

Tropical Storm Risk had this prediction for 36 hours wind fields at 13:00 hrs EST, showing it dropping slightly and crossing just north of Innisfail. These guys have proved pretty accurate in the past. Should add they work on the Saffir Simpson Scale so their Cat 5 is our Cat 4.

http://www.tropicalstormrisk.com/

Posted by: RWM's Daughter

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 18:06

[img:left][/img]
Posted by: RWM's Daughter

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 18:06

IDQP0005
Australian Government Bureau of Meteorology
Queensland
Tropical Cyclone Warning Centre

Media: The Standard Emergency Warning Signal should NOT be used with this
warning.

TOP PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 7
Issued by the Bureau of Meteorology, Brisbane
Issued at 4:53pm EST on Tuesday the 1st of February 2011

A Cyclone WARNING is current for coastal areas from Cape Melville to Sarina
extending inland to Georgetown and west of Charters Towers.

A Cyclone WATCH is current for coastal areas from Lockhart River to Cape
Melville and for the northern tropical interior.

The Cyclone WATCH from Sarina to Yeppoon has been cancelled.

At 4:00 pm EST Severe Tropical Cyclone Yasi, Category 3 was estimated to be
1020 kilometres east northeast of Cairns and 1020 kilometres east northeast of
Townsville moving west southwest at 34 kilometres per hour.

YASI IS A LARGE AND POWERFUL TROPICAL CYCLONE AND POSES A SERIOUS THREAT TO
NORTH QUEENSLAND COMMUNITIES

The Cyclone is expected to slowly intensify overnight and continue moving in a
west-southwesterly direction.

DAMAGING winds with gusts to 90 km/hr are expected to develop on the islands
during Wednesday morning, then extend onto the coast during the day, and
further inland across the northern tropical interior overnight.

Between Cooktown and Townsville these winds will become DESTRUCTIVE with gusts
in excess of 125km/hr late Wednesday afternoon and VERY DESTRUCTIVE with gusts
above 170 km/hr between Port Douglas and Cardwell during the evening as the
cyclone approaches.

As the centre approaches the coast sea levels between Cairns and Townsville will
rise significantly above the normal tide with damaging waves, strong currents
and flooding of low lying areas near the shoreline.

Flooding rains will develop from Cooktown to Sarina during Wednesday afternoon
and then extend inland overnight.


People between Cooktown and Sarina and extending inland to areas from Georgetown
to west of Charters Towers should immediately commence or continue preparations,
especially securing boats and property [using available daylight hours/before
nightfall].
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

People between Lockhart River and Cooktown and remaining tropical interior
should consider what action they will need to take if the cyclone threat
increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 4:00 pm EST:
.Centre located near...... 14.4 degrees South 154.9 degrees East
.Location accuracy........ within 55 kilometres
.Recent movement.......... towards the west southwest at 34 kilometres per hour
.Wind gusts near centre... 220 kilometres per hour and INTENSIFYING
.Severity category........ 3
.Central pressure......... 960 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 8:00 pm EST Tuesday 01 February.

This warning is also available through TV and Radio Broadcasts; the Bureau's
website at www.bom.gov.au or call 1300 659 212. The Bureau and the State
Emergency Service would appreciate this warning being broadcast regularly.
Posted by: Tempest

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 18:13

Originally Posted By: Raindammit
Latest (3:00pm) forecast by GFS:



I reckon GFS are on the money
Posted by: Learjet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 18:13

5pm NOAA 15 pass. Position is roughly 930km from Mackay (red +)at 41 degrees.

IR.



Last visible for the day from NOAA.

Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 18:13

Eye has vanished on the Vis shot, Yasi seems to be undergoing an ERC.
see link below.
http://www.nrlmry.navy.mil/tcdat/tc11/SH...1550E.100pc.jpg

learjet, There will be one or two other vis shots from the OLS sensors wont there?
Posted by: weather stalker

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 18:26

This was posted in the general thread:

Quote:
Originally Posted By: Bjelke
"Severe Tropical Cyclone Yasi, Category 3 was estimated to be 1020 kilometres east northeast of Cairns and 1020 kilometres east northeast of Townsville"

What's the problem here????
End

How is this possible? I believed the distance from both places would have been measured to the same 'point' in the system so I don't understand how it can be 1020km from two different locations in the exact same direction? Sorry if this is a really stupid question but the question isn't being answered in the general thread.


Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 18:34

Eye starting to consolidate after the interior featured eroded



Interesting that there is a channel forming outside the eyewall. This may impact on future intensity.

The infrared now starting to show an eye wrapping in as well.



So the system should go cat 4 in the next 12 hours - which isn't really rocket science as thats what the forecast has been saying all along.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 18:39

Originally Posted By: weather stalker
I believed the distance from both places would have been measured to the same 'point' in the system so I don't understand how it can be 1020km from two different locations in the exact same direction?


Eastnortheast spans from 057 degrees to 079 degrees on the compass (roughly). So one could be 060 degrees at 1020 km and another 075 degress at 1020 km and they would both be ENE.
Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 18:43

Yasi is almost a text book cyclone. Several people in the tech thread have commented that this system is following all the steps to the letter and has shown no signs of the usual erratic Coral Sea cyclones we are used to (STC Larry is an exception).

I mentioned on the general thread that Yasi has all the characteristics of an Atlantic hurricane with his smooth predictable path and life cycle (gradual turn poleward and steady forward motion). Could this be our 'perfect storm'.
Posted by: Brett Guy

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 18:51

Could be perfect. Is it just me or is Yasi start?ing to show Anular characteristics
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 18:58

The ocean heat content problem (or hopefully solution) is shown nicely below.



This is also identified in the recent technical bulletin.

The environment of low shear and good upper level outflow, assisted by an upper low to the south, is conducive for development, however the system is passing over an area of reduced ocean heat content which may be hindering intensification.

Dvorak intensity based on eye pattern [EIR B surround, LG/B elongated eye; VIS 1degree embedded distance but ragged subtraction] both giving DT=5.0, consistent with adjusted MET. Mean winds estimated at 85 knots [top end CI=5.0] supported by SATCON [95 knots 1min mean] as CIMMS AMSU estimates are higher than ADT.

Further intensification can be expected with low shear, upper outflow environment persisting until landfall. How much influence the ocean heat content has on the intensification process remains a factor of uncertainty.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 19:16

I'm not sure I follow what is reducing the "ocean heat content", the SSTs are similar, and the specific heat of the ocean does not change significantly (or does it?). If this is so, then what influences the OHC or is it a misnomer?
Posted by: point breaks

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 19:23

Originally Posted By: opplevelse
I'm not sure I follow what is reducing the "ocean heat content", the SSTs are similar, and the specific heat of the ocean does not change significantly (or does it?). If this is so, then what influences the OHC or is it a misnomer?


Considering there are times when out off the point here (Burleigh Heads) there is a noticeable difference between being there and on the beach. Add to the fact you can also feel cool currents occasional flow beneath you, on a large scale it def seems possible

EDIT. apologies if this comment is inappropriate for a tech thread.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 19:43

Originally Posted By: opplevelse
I'm not sure I follow what is reducing the "ocean heat content"

As it was explained to me (so this is second hand) the temperature of the ocen varies with depth. The sea surface temperature is just that - the top metre - maybe even mm if its measured from satellite.

When a cyclone moves though the massive waves and strong currents mix the water to 10's or 100's of metres deep. So if the warm water is only shallow, and its much colder below, then the temperatures drop dramatically and the amount of available energy decreases.


Yasi is moving quite quickly - so the amount of time is spends with this cold water affecting it is less than a slow moving storm.
Posted by: bazookabob

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 19:47

On the point of ocean heat, i know that heat effects intensity, and to some level intensity can effect steering, so is it thus okay to say that ocean heat can effect steering through it's effect on intensity?

EDIT thus would yasi passing through cooler water cause it to either slow or shift more southward?
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 19:58

Originally Posted By: He who once was ITN
Originally Posted By: opplevelse
I'm not sure I follow what is reducing the "ocean heat content"

As it was explained to me (so this is second hand) the temperature of the ocen varies with depth. The sea surface temperature is just that - the top metre - maybe even mm if its measured from satellite.

When a cyclone moves though the massive waves and strong currents mix the water to 10's or 100's of metres deep. So if the warm water is only shallow, and its much colder below, then the temperatures drop dramatically and the amount of available energy decreases.


Yasi is moving quite quickly - so the amount of time is spends with this cold water affecting it is less than a slow moving storm.
Ahhh of course, so it is essentially an integrated heat content of the layers of the ocean "available" to the cyclone. Very interesting, I never really considered that, thanks! I wonder how they measure it? By bouys / soundings?
Posted by: MikeM

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 20:22

It looks like it has slowed in the last frame or is going though an EWR. Anyone else confirm this ?
Posted by: Tempest

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 20:28

Someone on the other Yasi thread also mentioned about it slowing down
Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 21:00

Originally Posted By: MikeM
It looks like it has slowed in the last frame or is going though an EWR. Anyone else confirm this ?


There was some talk of an EWR and looks like it, but I am no expert.

EWRs are of course common with severe TCs.
Posted by: Ree

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 21:01

IDQP0005
Australian Government Bureau of Meteorology
Queensland
Tropical Cyclone Warning Centre

Media: The Standard Emergency Warning Signal should NOT be used with this
warning.

TOP PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 8
Issued by the Bureau of Meteorology, Brisbane
Issued at 8:00pm EST on Tuesday the 1st of February 2011

A Cyclone WARNING is current for island and coastal areas from Cape Melville to
Sarina, extending inland to Georgetown and to the west of Charters Towers.

A Cyclone WATCH is current for island and coastal areas from Lockhart River to
Cape Melville, and over the tropical interior.

At 7:00 pm EST Severe Tropical Cyclone Yasi, Category 4 was estimated to be
950 kilometres east northeast of Cairns and 950 kilometres east northeast of
Townsville moving west southwest at 30 kilometres per hour.

YASI IS LARGE AND POWERFUL TROPICAL CYCLONE AND POSES A SERIOUS THREAT TO NORTH
QUEENSLAND COMMUNITIES

The Cyclone will continue to intensify and move in a west-southwesterly
direction overnight.

DAMAGING winds with gusts to 90 km/hr are expected to develop on the islands
during Wednesday morning, then extend onto the coast during the day, and further
inland across the northern tropical interior overnight.

Between Cooktown and Ingham these winds will become DESTRUCTIVE with gusts in
excess of 125km/hr on Wednesday afternoon and VERY DESTRUCTIVE with gusts above
200 km/hr between Port Douglas and Cardwell during the evening as the cyclone
approaches. These VERY DESTRUCTIVE winds will extend onto the coastal ranges
including the Atherton Tablelands on Wednesday evening.

As the centre approaches and crosses the coast sea levels between Cairns and
Townsville will rise significantly above the normal tide with damaging waves,
strong currents and flooding of low lying areas in coastal parts.

Flooding rains will develop from Cooktown to Sarina during Wednesday afternoon
and then extend inland overnight.

People between Cooktown and Sarina and extending inland to areas from Georgetown
to west of Charters Towers should immediately commence or continue preparations,
especially securing boats and property.
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

People between Lockhart River and Cooktown and the remaining tropical interior
should consider what action they will need to take if the cyclone threat
increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 7:00 pm EST:
.Centre located near...... 14.6 degrees South 154.3 degrees East
.Location accuracy........ within 55 kilometres
.Recent movement.......... towards the west southwest at 30 kilometres per hour
.Wind gusts near centre... 230 kilometres per hour and INTENSIFYING
.Severity category........ 4
.Central pressure......... 950 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 11:00 pm EST Tuesday 01 February.

This warning is also available through TV and Radio Broadcasts; the Bureau's
website at www.bom.gov.au or call 1300 659 212. The Bureau and the State
Emergency Service would appreciate this warning being broadcast regularly.
Posted by: Steamy

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 21:11

RE It looks like it has slowed in the last frame or is going though an EWR. Anyone else confirm this ?

These two pictures are an hour apart and they are very similar.

7:32 Z on the left 8:32 Z on the right.



Uploaded with ImageShack.us
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 21:11

The automated dvorak thingy has Yasi reaching 6.4

2011FEB01 083200 4.3 972.9/ +2.9 / 72.2 4.3 4.3 6.4

I found an instruction kit on dvorak at www.mccrones.com/tropical/dvorak/Dvorak_Technique.ppt and tried it on



On slide 61 the instructions says white surround equals 6.0
On slide 64 it says work out the eye adjustment which I got to be 0 as it is white surround and medium gray eye
On slide 64 its says to take off 0.5 if there is an elongated eye.

So this gave me 5.5 as an answer.

I found a conversion sheet here .. http://www.cyclone.org.au/content/Appendix_A_conversions.pdf which suggests that 5.5 is 234km/hr which I think makes the system a category 4.

Anyone see anything I've done wrong?
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 21:12

I'd just like to note that I worked that out BEFORE the warning came out with an upgrade to category 4 and 230 km/hr!!!!
Posted by: !SCHUMMY!

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 21:17

i thought this is quite interesting, it show the MPI (Maximum Potential Intensity) in the Coral Sea, there are some solid 900's in front of YASI....

http://cimss.ssec.wisc.edu/tropic2/tropic.php#

what do you all think?

click on YASI and select MSLP in the top-right corner....

pic didnt work frown
Posted by: MareebaWeather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 21:47

Online scanner feeds from Far North Queensland
RadioReference Feeds

This includes:
Cairns Police
Far North Firecom
Marine & SES


---------------------------

Cyclone

Live Weather Data & Lightning Tracker
Posted by: S .O.

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 22:08

This lower SST's sound like a good thing , however the last time i looked at the Nino maps for sub sea surface temps i believe some parts of the western zone showed higher than normal sub surface temps and only average surface temps .
Now that TCY has gone Cat 4 and we will see swell wave periods approaching 12-13 secs ahead of the cyclones inner bands, maybe mixing waters together and upwelling. Could this lack of surface energy have no effect and it will still keep building .
Please correct me enlightened ones !! frown
Posted by: Rainwoman_08

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 22:13

Willis Is radar is OK. Just checked it.
Posted by: jss

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 22:19

It's rather hard to tell without microwave imagery, which is lacking at the moment. But since it's just reached cat 4 and contiuning to intensify, it's quite likely to see EWR cycles starting, should get at least one more in before it hits! Taking of disrupting the voritcity ring, I'm really hoping to see some eyewall mesovortices like with larry, maybe another paper grin not long till it's on radar.
Posted by: CraigA74

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 22:30

With the EWRC that may be happening,correct me if I'm wrong but will this inhibit intensification and possibly increase the actual size of the system even further?
Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 22:41



We really do take technology for granted. When you really think about it, it’s awesome how we can watch Yasi unfold on our computer screens with images taken from space during the night.
Posted by: jss

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 22:43

It's a cycle. As/if the eyewall recorganises, the convection about the eyewall is disrupted by low reflectivty inflow, weakening the winds about the eye region. Quite a few things can happen after a ERC, but it is not directly related to TC intensifcation or diameter. Wiki has a nice simple explanation with a few theories.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 22:49

LOL How many acronyms do you want for the same thing (an Eyewall Replacement Cycle)! I always thought it was just an ERC LOL smile

Anyway, yes, ERC's are often associated with a brief weakening of the system as the outer eyewall replaces the inner eyewall, but the storm will typically re-intensify rapidly. It is not at all surprising to see a storm of this size undergoing ERCs at this stage, and in fact given the small tight nature of the eye in the few Microwave shots we have actually been able to get, it is almost expected.

As was mentioned earlier in the thread a second "trough" formed outside the main eye. This is the first step of an ERC as an outer eyewall forms and sucks moisture away from the inner eyewall, causing it to collapse.

Anyway, Yasi has probably undergone a few ERCs while the eye was covered by the CDO, and is possibly undergoing one now. You don't need to rely on the MW data to tell either. You can often tell with visible sat shots with the sun at an oblique angle (so you can pick up surface features on the CDO. Or at night on the microwave shots.

Of course the best way to tell is if you have radar of the eye, and we should do in a few hours as it approaches Willis island smile
Posted by: StormySpott

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 22:53

Mods, if you don't mind, I'll post this video link of this American guy who I believe is a Met doing an analysis of various Weather events around the world and Australia and posting his thoughts via You Tube. Some technical data can be found in his comments.

Latest Analysis of STC Yasi
Posted by: jss

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 22:59

If there's any vortex rossby wave activity I might post of some wavelet anaylsis if anyones interested as the tc comes within range tomorrow, probably just the fourier analysis of the eyewall as it's the most interesting. If activity is strong enough, true storm surge heights could become very 'unresolved' indeed. *Avoids media*
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 23:09

Hmm gunna try my luck with this one



Slide 62 say pick the (thick) surrounding shade & I think it has to be light grey as black is too thin -> 5.0
Slide 64 is eye adjust and that is the thin surrounding shade which is black and the inside shade is off white -> + 0.5

Since the eye is round that makes a 5.5 - same as before -> 234 km/hr.

If that white wraps all the way round it would be 6.0 + 0.5 which would be a scary 290! Fortunately not there yet though.
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 23:12

Originally Posted By: opplevelse
LOL How many acronyms do you want for the same thing (an Eyewall Replacement Cycle)! I always thought it was just an ERC LOL smile

Anyway, yes, ERC's are often associated with a brief weakening of the system as the outer eyewall replaces the inner eyewall, but the storm will typically re-intensify rapidly. It is not at all surprising to see a storm of this size undergoing ERCs at this stage, and in fact given the small tight nature of the eye in the few Microwave shots we have actually been able to get, it is almost expected.

As was mentioned earlier in the thread a second "trough" formed outside the main eye. This is the first step of an ERC as an outer eyewall forms and sucks moisture away from the inner eyewall, causing it to collapse.

Anyway, Yasi has probably undergone a few ERCs while the eye was covered by the CDO, and is possibly undergoing one now. You don't need to rely on the MW data to tell either. You can often tell with visible sat shots with the sun at an oblique angle (so you can pick up surface features on the CDO. Or at night on the microwave shots.

Of course the best way to tell is if you have radar of the eye, and we should do in a few hours as it approaches Willis island smile


does a wobble like we sometimes see on the IR sat indicate a EWR?
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 23:14

Originally Posted By: uq-wx
If there's any vortex rossby wave activity I might post of some wavelet anaylsis if anyones interested as the tc comes within range tomorrow, probably just the fourier analysis of the eyewall as it's the most interesting. If activity is strong enough, true storm surge heights could become very 'unresolved' indeed. *Avoids media*


yeah, that would be awesome grin
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 23:17

So really its actually stronger, as its giving the same result as before but this one has a much better eye structure.

Originally Posted By: He who once was ITN
Hmm gunna try my luck with this one



Slide 62 say pick the (thick) surrounding shade & I think it has to be light grey as black is too thin -> 5.0
Slide 64 is eye adjust and that is the thin surrounding shade which is black and the inside shade is off white -> + 0.5

Since the eye is round that makes a 5.5 - same as before -> 234 km/hr.

If that white wraps all the way round it would be 6.0 + 0.5 which would be a scary 290! Fortunately not there yet though.

Posted by: !SCHUMMY!

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 23:22

ok..take 2! smile Here is the MPI (Maximum Potential Intensity) progged for the Coral Sea ahead of STC YASI



it really shows what she (YASI) is capable of if conditions are perfect for further rapid intensification....which is a possibility after the current EWRC (Eye Wall Replacement Cycle)
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 23:23

Originally Posted By: uq-wx
If there's any vortex rossby wave activity I might post of some wavelet anaylsis if anyones interested as the tc comes within range tomorrow, probably just the fourier analysis of the eyewall as it's the most interesting. If activity is strong enough, true storm surge heights could become very 'unresolved' indeed. *Avoids media*
I'd be interested! I've never really understood the motivation behind the study of VRW, I thought it was essentially an academic exercise. I can see how it may somehow be useful in helping understand wind distributions in the inner spiral bands but even then, what is the practical application- or isnt there any? Is it just to aid our understanding of the physical phenomena (a worthwhile goal in it-self). Or is the ultimate goal microscale or even storm scale forecasts of TC wind fields for application in the real world?
Posted by: crikey

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 23:37

20 metre waves of Nth queensland coastline +6.00am wed morning 2/2/2011 just off coastline
What does this data mean?
http://www.weatheronline.co.uk/marine/weather?LEVEL=5&LANG=en&MENU=0&TIME=30&MN=gfs&CONT=aupa
Posted by: Subtropical

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 23:45

Could TC Yasi intensify to a Category 5?

How valid is BOM's Ann Farrell's statement on TC Yasi's potential severity reported in The Sydney Morning Herald? BOM senior forecaster Ann Farrell said Yasi was continuing to intensify and she could not rule out the chance of it reaching category five.‘‘It is possible it could reach category five intensity, and that would push winds up to around the 300km/h mark,’’ Ms Farrell said. Yasi could become category five monster

The Australian Bureau of Meteorology tropical cyclone severity categories

Category 5 ≥280 km/h (Maximum wind gusts), ≥200 km/h (Maximum sustained winds)
Category 4 225-279 km/h (Maximum wind gusts), 160-199 km/h (Maximum sustained winds)
Category 3 170-224 km/h (Maximum wind gusts), 118-159 km/h (Maximum sustained winds)
Category 2 125-169 km/h (Maximum wind gusts), 89-117 km/h (Maximum sustained winds)
Category 1 90-124 km/h (Maximum wind gusts), 63-88 km/h (Maximum sustained winds)
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 01/02/2011 23:49

If the white band were to wrap around in the infrared image then I think it would be 6.5 which is 290 - but I'm no expert and am just following the rules in the dvorak powerpoint
Posted by: marakai

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 00:06

Latest chart is out with not much difference so far http://www.bom.gov.au/products/IDQ65002.shtml seeming to become more consistent with each run.
Posted by: Dave-Wx

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 00:07

Certainly going by the last 2 IR frames (1030 and 1130UTC) I think Yasi has bumped up another notch...be interesting Mr ITN if you had a look at the 1130UTC frame (or of course wait for the next one in 10-20 mins smile ) Actually there we go...260km/h in the latest TC advice, certainly along my lines of thinking!

Am wondering if the missing piece in the puzzle for Yasi trying to be a Cat 5 will be the higher energy just off the Cairns coastline as in the image posted by ITN a little earlier (http://i53.tinypic.com/1q3jno.gif). Yasi is steadily going to move into that area over the next 6 hours. Given that Yasi is already a high Cat 4, that would make the odds of Cat 5 between now and landfall certainly better than 50% I reckon.

Edit: Also just noticed that the latest track map has landfall (10pm tomorrow night) as 1 hour after high tide...just about couldn't time it any worse could you Yasi!
Posted by: marakai

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 00:07

IDQ20018
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1303 UTC 01/02/2011
Name: Severe Tropical Cyclone Yasi
Identifier: 14U
Data At: 1200 UTC
Latitude: 15.0S
Longitude: 153.1E
Location Accuracy: within 20 nm [35 km]
Movement Towards: west southwest [252 deg]
Speed of Movement: 18 knots [34 km/h]
Maximum 10-Minute Wind: 100 knots [185 km/h]
Maximum 3-Second Wind Gust: 140 knots [260 km/h]
Central Pressure: 940 hPa
Radius of 34-knot winds NE quadrant: 160 nm [295 km]
Radius of 34-knot winds SE quadrant: 250 nm [465 km]
Radius of 34-knot winds SW quadrant: 250 nm [465 km]
Radius of 34-knot winds NW quadrant: 120 nm [220 km]
Radius of 48-knot winds NE quadrant: 90 nm [165 km]
Radius of 48-knot winds SE quadrant: 120 nm [220 km]
Radius of 48-knot winds SW quadrant: 120 nm [220 km]
Radius of 48-knot winds NW quadrant: 60 nm [110 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T6.0/6.0/D1.0/24HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 210 nm [390 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 02/0000: 16.1S 149.6E: 050 [095]: 105 [195]: 937
+24: 02/1200: 17.1S 146.0E: 080 [150]: 105 [195]: 937
+36: 03/0000: 18.4S 142.8E: 110 [205]: 050 [095]: 986
+48: 03/1200: 19.6S 140.0E: 130 [240]: 030 [060]: 998
+60: 04/0000: 20.8S 137.5E: 160 [295]: 025 [045]: 1001
+72: 04/1200: 21.5S 135.4E: 190 [350]: 025 [045]: 1000
REMARKS:
Yasi has intensified in the last 6 hours. The environment of low shear and good
upper level outflow, assisted by an upper low to the south, is conducive to
maintaining current intensity. There is the possibility of some further
intensification before landfall.

Dvorak intensity based on eye pattern [EIR B surround, OW eye] giving DT=6.0,
consistent with adjusted MET. Mean winds estimated at 100 knots.

Forecast motion is steady to the west southwest with a persisting mid-level
ridge to the south. Models are quite consistent with the forecast motion.

The combined factors of being intense, large, and motion at 18 knots are
conducive for greater wave/swell generation to the south of of the forecast
track.

With the expectation of being a large and intense system, cyclone intensity may
be maintained further inland than normal.
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 00:08

Originally Posted By: He who once was ITN
If the white band were to wrap around in the infrared image then I think it would be 6.5 which is 290 - but I'm no expert and am just following the rules in the dvorak powerpoint


did you see the one Scott A posted in the Yazi chat thread? Can you please do one on that, it was a beauty!!
Posted by: Rhubarb

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 00:09

Hope you'll be interested in this. It's from the Waverider bouy at Cairns.

Instrument: Datawell 0.7m Waverider Buoys
Date of installation: 02-05-1975
Current location: Latitude: 16° 43.984' S Longitude: 145° 42.645' E
Water depth: 9

http://www.derm.qld.gov.au/environmental...ave_monitoring/

Posted by: Scottie A

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 00:11

Guys here is the latest 1214Z BD Image you guys definitely ITN would be much better than me at working out a D calculation.. especially at this hour.



Colour IR aswell

Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 00:15

Originally Posted By: marakai
IDQ20018
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1303 UTC 01/02/2011
Name: Severe Tropical Cyclone Yasi
Identifier: 14U
Data At: 1200 UTC
Latitude: 15.0S
Longitude: 153.1E
Location Accuracy: within 20 nm [35 km]
Movement Towards: west southwest [252 deg]
Speed of Movement: 18 knots [34 km/h]
Maximum 10-Minute Wind: 100 knots [185 km/h]
Maximum 3-Second Wind Gust: 140 knots [260 km/h]
Central Pressure: 940 hPa



IMO, Yazi will easily get to the forecast 925hPa. Its been growing at about 20hPa/day... still 24 hours+/- until forecast landfall plus a nice little nitros injection of sst's just off the coast.
Posted by: !SCHUMMY!

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 00:27

here is the tech bulletin....YASI is a mid CAT 4 now, wouldnt surprise me to see her a high CAT 4 by the 5am update or even a low CAT 5 by lunchtime....just gotta wait and see....


IDQ20018
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1321 UTC 01/02/2011
Name: Severe Tropical Cyclone Yasi
Identifier: 14U
Data At: 1200 UTC
Latitude: 15.0S
Longitude: 153.1E
Location Accuracy: within 20 nm [35 km]
Movement Towards: west southwest [252 deg]
Speed of Movement: 18 knots [34 km/h]
Maximum 10-Minute Wind: 100 knots [185 km/h]
Maximum 3-Second Wind Gust: 140 knots [260 km/h]
Central Pressure: 940 hPa
Radius of 34-knot winds NE quadrant: 160 nm [295 km]
Radius of 34-knot winds SE quadrant: 250 nm [465 km]
Radius of 34-knot winds SW quadrant: 250 nm [465 km]
Radius of 34-knot winds NW quadrant: 120 nm [220 km]
Radius of 48-knot winds NE quadrant: 90 nm [165 km]
Radius of 48-knot winds SE quadrant: 120 nm [220 km]
Radius of 48-knot winds SW quadrant: 120 nm [220 km]
Radius of 48-knot winds NW quadrant: 60 nm [110 km]
Radius of 64-knot winds: 40 nm [70 km]
Radius of Maximum Winds: 20 nm [35 km]
Dvorak Intensity Code: T6.0/6.0/D1.0/24HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 210 nm [390 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 02/0000: 16.1S 149.6E: 050 [095]: 105 [195]: 937
+24: 02/1200: 17.1S 146.0E: 080 [150]: 105 [195]: 937
+36: 03/0000: 18.4S 142.8E: 110 [205]: 050 [095]: 986
+48: 03/1200: 19.6S 140.0E: 130 [240]: 030 [060]: 998
+60: 04/0000: 20.8S 137.5E: 160 [295]: 025 [045]: 1001
+72: 04/1200: 21.5S 135.4E: 190 [350]: 025 [045]: 1000
REMARKS:
Yasi has intensified in the last 6 hours. The environment of low shear and good
upper level outflow, assisted by an upper low to the south, is conducive to
maintaining current intensity. There is the possibility of some further
intensification before landfall.

Dvorak intensity based on eye pattern [EIR B surround, OW eye] giving DT=6.0,
consistent with adjusted MET. Mean winds estimated at 100 knots.

Forecast motion is steady to the west southwest with a persisting mid-level
ridge to the south. Models are quite consistent with the forecast motion.

The combined factors of being intense, large, and motion at 18 knots are
conducive for greater wave/swell generation to the south of of the forecast
track.

With the expectation of being a large and intense system, cyclone intensity may
be maintained further inland than normal.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 01/1900 UTC by Brisbane
TCWC.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 00:50

Originally Posted By: opplevelse
Eye has vanished on the Vis shot, Yasi seems to be undergoing an ERC.
see link below.
http://www.nrlmry.navy.mil/tcdat/tc11/SH...1550E.100pc.jpg

learjet, There will be one or two other vis shots from the OLS sensors wont there?

Yep there were actually 2 more OLS shots ... not very good, but meh. The one below is the last decent one of the day.


It shows a filled eye but some other structures in the CDO which would indicate an ERC, particularly on the western side of the storm.

This is the latest MW shot from metopa around 2.5hrs ago. It also indicates a concentric eyewall structure, which is often a feature during an ERC ... but normally that only occurs with much smaller inner eyes. In this case the inner eye is still huge, so I wonder if it might just be the low resolution. Some of the ERC experts like UQ-WX would have a better insight.



Inner bands just coming into the 512km comp radar view now ... it will be an interesting day ahead for storm watching.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 00:51

Originally Posted By: Scottie A
Guys here is the latest 1214Z BD Image you guys definitely ITN would be much better than me at working out a D calculation

Umm ok .. well its white all the way around .. so slide 62 says 6.0 .. and slide 64 says white all the way round with off white in the middle is +0.5 .. and that adds up to 6.5 or 290! But don't quote me or anything 'cos I've probably stuffed up somewhere - always use what the experts say.

For those who want to play along at home I found the rules at http://www.mccrones.com/tropical/dvorak/Dvorak_Technique.ppt

... and the automated outputs showing 6.0 to 6.7 ..

2011FEB01 083200 4.3 972.9/ +2.9 / 72.2 4.3 4.3 6.4

2011FEB01 093200 4.3 972.9/ +2.9 / 72.2 4.3 4.3 6.0

2011FEB01 103200 4.7 964.0/ +2.8 / 82.2 4.7 6.0 6.1

2011FEB01 113200 5.1 954.2/ +2.8 / 92.4 5.1 6.0 6.5

2011FEB01 121400 5.5 943.8/ +2.8 /102.0 5.5 6.0 6.7

2011FEB01 123200 5.6 941.0/ +2.8 /104.6 5.6 6.0 6.4
Posted by: !SCHUMMY!

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 01:00

here is what STC YASI looks like now....

Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 01:10

Looks like its going xyz direction

Having watched TC's for the last 16 years - since I got interested in them at Uni - and having been lucky to speak to a few people in the business who really know what they are doing - I really do need to say some about the "I think its going in this direction" caper that strikes in every major system.

The experts don't just look at the last hour or two hours of motion - they use the last 6 or 9 hours. Trochoidal motion is very very common in TCs (http://en.wikipedia.org/wiki/Tropical_cyclone_track_forecasting) - short amplitude variations in track mask the longer term motion. Its a bit like trying to track a light on a bicycle wheel.

Cyclone will dodge up and down with a period of about 3 to 9 hours .. so thats why a longer term track is taken. This is especially true when it gets on radar.

So can we please use a modicum of sense when saying its this way .. its that way .. cos its most likely just what it was doing 3 hours ago. Rant ends.
Posted by: neptune1

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 01:35

If you have a look at this link http://www.goes.noaa.gov/sohemi/sohemiloops/shirgmscol.html , my thoughts are that Yasi had a eye replacement just recently hence why the sudden drop in pressure to 940 hpa, if that the case it should increase in intensity for several hours? any thoughts?

Just to get us on the topic again.
Posted by: Willoughby

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 01:36

24 HRS, VALID AT:
021200Z --- 17.1S 146.2E
MAX SUSTAINED WINDS - 130 KT, GUSTS 160 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 050 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 100 NM NORTHEAST QUADRANT
110 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT
210 NM SOUTHEAST QUADRANT
210 NM SOUTHWEST QUADRANT
190 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 245 DEG/ 17 KTS
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 01:45

Originally Posted By: neptune1
If you have a look at this link http://www.goes.noaa.gov/sohemi/sohemiloops/shirgmscol.html , my thoughts are that Yasi had a eye replacement just recently hence why the sudden drop in pressure to 940 hpa, if that the case it should increase in intensity for several hours? any thoughts?

Just to get us on the topic again.
Yep pretty much. It should tighten up again now. It is still a bit lopsided towards the NE quadrant (see this IR shot, not the one below which is older) but I would expect it will be a lot more symmetrical tomorrow morning.

I'll save this shot for UQ-WX ... some interesting features inside the eye ... just a pity this is the 1km IR shot, would have been facinating if it was the 250m Vis shot. This is a MODIS IR shot from Terra at 1215Z.
Posted by: Subtropical

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 02:13

JTWC track and data showing wind gusts at 160 knots (296.3 km/hour).

Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 02:27

The latest Automated Dvorak http://cimss.ssec.wisc.edu/tropic2/real-time/adt/11P-list.txt has this system at between 6.5 and 6.7. That is wind gust up to 305 km/hr. This system is going to go to Category 5.

I hope mods don't mind me sharing a personal opinion here. If anyone in the Cairns to Innisfail area and nearby regions has the slightest doubt that their house is not rated to take a category 5 system, or is anywhere close to the storm tide threat areas - leave. You can drive a long way in 6 hours - even driving slowly you can be 300 km away.

This will not be a fun experience - it will be terrifying and life threatening.

http://www.youtube.com/watch?v=H9VpwmtnOZc.

http://www.youtube.com/watch?v=l9vDSWugz08

ITN.
Posted by: CycloneJosh

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 02:35

Wow-- that is the most ominous forecast I've seen from the JTWC. I mean, 130 kt is just really extreme. That's flirting with the American Cat 5!

It's interesting how perfectly the BoM and JTWC forecasts match-- down to the hours and the kilometer.
Posted by: Learjet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 02:37

1:15am NOAA 19 pass.

734km at 28 degrees from Mackay (Red + indicates receiving station).

Posted by: Jajang

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 02:55

IDQP0005
Australian Government Bureau of Meteorology
Queensland
Tropical Cyclone Warning Centre

Media: The Standard Emergency Warning Signal should NOT be used with this
warning.

TOP PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 10
Issued by the Bureau of Meteorology, Brisbane
Issued at 1:49am EST on Wednesday the 2nd of February 2011

A Cyclone WARNING is current for island and coastal areas from Cape Melville to
Sarina, extending inland to east of Croydon to Hughenden.

A Cyclone WATCH is current for coastal areas from Lockhart River to Cape
Melville, and in the tropical interior north of Winton to Sarina.

At 1:00 am EST Severe Tropical Cyclone Yasi, Category 4 was estimated to be
740 kilometres east northeast of Cairns and 750 kilometres northeast of
Townsville moving west southwest at 30 kilometres per hour.

YASI IS A LARGE AND POWERFUL TROPICAL CYCLONE AND POSES A SERIOUS THREAT TO
NORTH QUEENSLAND COMMUNITIES

The Cyclone will continue to move in a west-southwesterly direction during
today, and may intensify slightly.

DAMAGING WINDS with gusts to 90 km/hr are expected to develop on coastal islands
later this morning, then extend onto the coast during the day, and further
inland across the northern tropical interior overnight.

Between Cooktown and Ingham these winds will become DESTRUCTIVE with gusts in
excess of 125km/hr during the afternoon and VERY DESTRUCTIVE with gusts above
200 km/hr between Port Douglas and Cardwell during the evening as the cyclone
approaches. These VERY DESTRUCTIVE winds will extend onto the coastal ranges
including the Atherton Tablelands this evening.

As the centre approaches and crosses the coast SEA LEVELS between Cairns and
Townsville will rise significantly above the normal tide with DAMAGING WAVES,
STRONG CURRENTS and FLOODING of low lying areas in coastal parts.

FLOODING RAINS will develop from Cooktown to Sarina during the afternoon and
then extend inland overnight.

People between Cape Melville to Sarina, extending inland to east of Croydon to
Hughenden should immediately commence or continue preparations, especially
securing boats and property.
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

People between Lockhart River to Cape Melville, and in the tropical interior
north of Winton to Sarina should consider what action they will need to take if
the cyclone threat increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 1:00 am EST:
.Centre located near...... 15.3 degrees South 152.5 degrees East
.Location accuracy........ within 30 kilometres
.Recent movement.......... towards the west southwest at 30 kilometres per hour
.Wind gusts near centre... 270 kilometres per hour
.Severity category........ 4
.Central pressure......... 935 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 5:00 am EST Wednesday 02 February.

This warning is also available through TV and Radio Broadcasts; the Bureau's
website at www.bom.gov.au or call 1300 659 212. The Bureau and the State
Emergency Service would appreciate this warning being broadcast regularly.
Posted by: Subtropical

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 03:03

Issued at 1:52 am EST Wednesday 2 February 2011. Refer to Tropical Cyclone Advice Number 10.

Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 03:03

At least tracking becomes easier - until Willis Island falls over

Posted by: Severely Tall

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 03:30

Very concerned on the upgrade from the JTWC, she is flirting with SSHS category 5, and given the recent apparent replacement cycle (though I am not sure it may just be a formative phase as she still is intensifying and had some issues with the positioning of the LLCC which left her slightly off axis due to her large size, meaning a spinup delay which means the wind field will continue to adjust up to match the cyclones features) there is still the potential to bomb the last little bit before landfall and make it well over that threshold...expect to see sub 920mb core pressure if thats the case...the slowing down has really played towards allowing this intensification. Starting to see a really impressive symmetry develop which will probably lead to a Dvorak upgrade into the 7s...I don't think she has time to get much further but either way its going to be a very bad coastal impact given the surge potential.
Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 05:10

currently CIMSS have it down at 922hPa and 120knts sustained!
Posted by: MareebaWeather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 06:01

I'm starting to pick up lightning on the lightning tracker

http://www.gorgecreekorchards.com.au/wx6.html

----------------------
Mareeba - Queensland - Australia
Live Weather Data & Lightning Tracker
Posted by: ColdFront

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 06:01

IDQP0005
Australian Government Bureau of Meteorology
Queensland
Tropical Cyclone Warning Centre

Media: Transmitters broadcasting to coastal areas between Cape Melville to
Sarina and inland areas east of Croydon to Hughenden are requested to USE THE
STANDARD EMERGENCY WARNING SIGNAL before broadcasting this warning.

TOP PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 11
Issued by the Bureau of Meteorology, Brisbane
Issued at 5:01am EST on Wednesday the 2nd of February 2011

A Cyclone WARNING is current for island and coastal areas from Cape Melville and
Sarina, extending inland to Croydon and Hughenden.

A Cyclone WATCH is current for coastal areas from the remaining tropical
interior east of Camooweal and north of Winton.

At 4:00 am EST Severe Tropical Cyclone Yasi, Category 5 was estimated to be
650 kilometres east northeast of Cairns and 650 kilometres northeast of
Townsville moving west southwest at 30 kilometres per hour.

SEVERE TC YASI IS A LARGE AND VERY POWERFUL TROPICAL CYCLONE AND POSES AN
EXTREMELY SERIOUS THREAT TO LIFE AND PROPERTY WITHIN THE WARNING AREA,
ESPECIALLY BETWEEN PORT DOUGLAS AND TOWNSVILLE.

THIS IMPACT IS LIKELY TO BE MORE LIFE THREATENING THAN ANY EXPERIENCED DURING
RECENT GENERATIONS.

The Cyclone has now reached CATEGORY 5 and will continue to move in a
west-southwesterly direction during today.

Coastal residents within the warning, and particularly between Port Douglas and
Townsville are specifically warned of an EXTREMELY DANGEROUS sea level rise
[i.e. storm tide] as the cyclone approaches and crosses the coast. The sea is
likely to steadily rise up to a level which will be VERY DANGEROUSLY above the
normal tide, with EXTREMELY DAMAGING WAVES, strong currents and flooding of
low-lying areas extending some way inland. People living in areas likely to be
affected by this flooding should take measures to protect their property as much
as possible, and be prepared to follow instructions regarding evacuation of the
area if advised to do so by authorities.

DAMAGING WINDS with gusts to 90 km/hr are expected to develop on coastal islands
later this morning, then extend onto the coast during the day, and further
inland across the northern tropical interior overnight.

Between Cooktown and Ingham these winds will become DESTRUCTIVE with gusts in
excess of 125km/hr during the afternoon and VERY DESTRUCTIVE with gusts above
280 km/hr between Port Douglas and Cardwell during the evening as the cyclone
approaches. These VERY DESTRUCTIVE winds can also occur on the seaward side of
hills to the north of the cyclone and are also forecast to reach the Atherton
Tablelands.

FLOODING RAINS will develop from Cooktown to Sarina during the afternoon and
then extend inland overnight.

People between Cape Melville and Sarina, extending inland to Croydon and
Hughenden should complete preparations quickly and be prepared to shelter in a
safe place.
- Boats and outside property should be secured.
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

People about the remaining tropical interior east of Camooweal and north of
Winton should consider what action they will need to take if the cyclone threat
increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 4:00 am EST:
.Centre located near...... 15.7 degrees South 151.7 degrees East
.Location accuracy........ within 20 kilometres
.Recent movement.......... towards the west southwest at 30 kilometres per hour
.Wind gusts near centre... 295 kilometres per hour
.Severity category........ 5
.Central pressure......... 924 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 8:00 am EST Wednesday 02 February.

This warning is also available through TV and Radio Broadcasts; the Bureau's
website at www.bom.gov.au or call 1300 659 212. The Bureau and the State
Emergency Service would appreciate this warning being broadcast regularly.
Posted by: ColdFront

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 06:02

...and from that update...

SEVERE TC YASI IS A LARGE AND VERY POWERFUL TROPICAL CYCLONE AND POSES AN
EXTREMELY SERIOUS THREAT TO LIFE AND PROPERTY WITHIN THE WARNING AREA,
ESPECIALLY BETWEEN PORT DOUGLAS AND TOWNSVILLE.

THIS IMPACT IS LIKELY TO BE MORE LIFE THREATENING THAN ANY EXPERIENCED DURING
RECENT GENERATIONS.
Posted by: P.K.

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 06:08

Upgraded to a 115kt cat 5 in the latest technical bulletin.

AXAU21 ABRF 011905
IDQ20018
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 1905 UTC 01/02/2011
Name: Severe Tropical Cyclone Yasi
Identifier: 14U
Data At: 1800 UTC
Latitude: 15.7S
Longitude: 151.7E
Location Accuracy: within 10 nm [20 km]
Movement Towards: west southwest [241 deg]
Speed of Movement: 15 knots [29 km/h]
Maximum 10-Minute Wind: 115 knots [215 km/h]
Maximum 3-Second Wind Gust: 160 knots [295 km/h]
Central Pressure: 924 hPa
Radius of 34-knot winds NE quadrant: 190 nm [350 km]
Radius of 34-knot winds SE quadrant: 250 nm [465 km]
Radius of 34-knot winds SW quadrant: 280 nm [520 km]
Radius of 34-knot winds NW quadrant: 190 nm [350 km]
Radius of 48-knot winds NE quadrant: 90 nm [165 km]
Radius of 48-knot winds SE quadrant: 130 nm [240 km]
Radius of 48-knot winds SW quadrant: 130 nm [240 km]
Radius of 48-knot winds NW quadrant: 60 nm [110 km]
Radius of 64-knot winds: 40 nm [70 km]
Radius of Maximum Winds: 15 nm [30 km]
Dvorak Intensity Code: T6.5/6.5/D1.5/24HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 220 nm [405 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 02/0600: 16.8S 148.1E: 050 [095]: 115 [215]: 924
+24: 02/1800: 17.9S 144.7E: 080 [150]: 065 [120]: 976
+36: 03/0600: 19.3S 141.6E: 110 [205]: 040 [075]: 993
+48: 03/1800: 20.3S 139.1E: 130 [240]: 030 [055]: 999
+60: 04/0600: 21.6S 136.8E: 160 [295]: 025 [045]: 1001
+72: 04/1800: 21.5S 134.7E: 190 [350]: 025 [045]: 1000
REMARKS:
Yasi has developed over the last 12 hours. DT based on eye pattern with white
surround with an off white eye average over 3 hours.

Forecast to remain at this intensity until landfall in a low shear and
favourable environment.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 02/0100 UTC by Brisbane
TCWC.
Posted by: Canberra's Weather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 07:11

Regarding warnings of an extreme storm surge, the danger level depends on whether you are on a floodplain or whether you are on a bit of a slope am I correct? How high will it be above AHD?
Posted by: Things

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 07:37

I don't think I've ever seen so many "Dangerous" and "Destructive" in a BoM forecast before. Really worried ...
Posted by: Rocky Raccoon

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 07:52

I have just been looking at the radar loop at Willis Island
It is clearly revealing the eye.

Willis Island radar loop
Posted by: dlcat1

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 07:57

Apologies if this isn't appropriate, but can anyone explain what I'm seeing with wind direction here at Willis Island? http://www.bom.gov.au/products/IDQ60801/IDQ60801.94299.shtml

I note the wind speed is still pretty much constant but the wind has appeared to swing through 180 degrees.

Is this just likely to be damage to the instrument or is there another explanation?

Cheers all.
Posted by: 56craigl

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:00

Originally Posted By: dlcat1
Apologies if this isn't appropriate, but can anyone explain what I'm seeing with wind direction here at Willis Island? http://www.bom.gov.au/products/IDQ60801/IDQ60801.94299.shtml

I note the wind speed is still pretty much constant but the wind has appeared to swing through 180 degrees.

Is this just likely to be damage to the instrument or is there another explanation?

Cheers all.


Probably has to do withe the time delay on the public images from Willis ie the eye is much closer than the image shows, IMHO ;-)
Posted by: camshaft

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:02

This is deadset somthing to remember, starting to look like a repeat of 1899 events. willis sustaining over 100k winds gust 140k
Posted by: Scud

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:06

Originally Posted By: dlcat1
Apologies if this isn't appropriate, but can anyone explain what I'm seeing with wind direction here at Willis Island? http://www.bom.gov.au/products/IDQ60801/IDQ60801.94299.shtml

I note the wind speed is still pretty much constant but the wind has appeared to swing through 180 degrees.

Is this just likely to be damage to the instrument or is there another explanation?

Cheers all.


The latest radar image from Willis Is is from 10 minutes ago (2050 UTC time) which definitely shows the eye still to the east of the radar site. Winds shouldn't be from the north so my guess is there is something wrong with the equipment. I hope the readings aren't affected by it. The eye looks like it will pass right over the top, would be amazing to see the values coming out from it.
Posted by: mattincairns

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:09

?Guys tell me with its interaction with land could this kick it W or wnw
Posted by: Colin Maitland

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:10

Some info on TC Yasi and comparison to TC Tracy from the Sydney Morning Herald

http://www.smh.com.au/environment/weathe...tml?from=smh_sb


Category five Cyclone Yasi's size and power will dwarf Cyclone Tracy, the most devastating storm in Australian history, and could cause even more widespread destruction.

Tracy struck Darwin in the early hours of Christmas Day in 1974, killing 71 people including 49 in the city and a further 22 at sea.

The majority of buildings in the Northern Territory capital were destroyed and a mass exodus saw the population plummet from about 48,000 to 10,500.
Advertisement: Story continues below
Flood map


Weatherzone meteorologist Brett Dutschke said Cyclone Yasi was the largest cyclone he had ever observed in Australian waters on satellite images.

Overnight, Yasi was upgraded to a category five cyclone.

"The area that it's covering is massive and to see it so close to Australia, even 1000 kilometres away, is a bit haunting," Mr Dutschke said.

"It's definitely something I've not seen before."

And Yasi made Cyclone Tracy - the storm that destroyed Darwin in 1974 - pale in comparison.

"It's a huge contrast to Tracy. Tracy was a much smaller cyclone, a lot more compact and it just happened to pass directly over a major populated area," Mr Dutschke said.

"[Tracy] was a similar intensity to this one, but Yasi is much larger so it probably only has to get within a few hundred kilometres of a populated area and it could cause similar damage.

"It doesn't have to be as choosy as Tracy with its accuracy."

Mr Dutschke said such a severe cyclone was "always on the cards" during the La Nina weather pattern, because ocean surface temperatures were warmer than normal.

And Cyclone Yasi was so powerful, it could remain a cyclone even after it had reached the outback.

"The more intense they are when they make landfall, the further they need to go [inland] before they are no longer a cyclone," Mr Dutschke said.

"It's probably going to have to go 500 kilometres inland before it's no longer of a cyclone intensity.

"It can effectively be desert that far inland."

Once it reaches landfall, Yasi is expected to follow Cyclone Anthony's lead and head southwest.

Mr Dutschke said the effects of Yasi could be felt as far away as Adelaide.

"It will bring a lot of moisture and there's a reasonable chance for flooding along the Murray [River]," he said.

By comparison Cyclone Larry, which caused $1.5 billion worth of damage to Innisfail and surrounds, was a mid-level category four system when it hit in 2006.

"This of course is not only a system now tracking as more intense than Cyclone Larry, it is significantly larger than Cyclone Larry," Premier Anna Bligh said yesterday.
[i][/i]
Posted by: Rhubarb

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:33

Checked up on Cyclone Mahina. It had a recorded pressure of 914 hpa when it approached the coast at Bathurst Bay at about 4.30am on 22 March 1899 and ships logs recorded a pressure of 926 hpa.
Posted by: nrivers2

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:38

Hi All,
New at this ,please be patient with me...lol,
What is the chances of the gold coast /northern nsw seeing any of the current situation?
regards ,dave
Posted by: 56craigl

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:40

Checking Willis radar latest, noticed that eye is compacting. About to undergo EWR?
Posted by: Things

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:43

Can anyone give an update on movement? Going by the radar it seems to be going West at the moment ...
Posted by: Inclement Weather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:45

I've re-posted the following here as it will just get lost on the chat thread. It is important to especially read just what a Cat 5 system is capable of doing below (See below):

The following is a copy of the Hurricane Warning for Hurricane Katrina on the 28th August 2005. It is interesting to read in retrospect in camparison to the current warning for Yasi. Make no mistake, the similarities are striking and sobering. Bear in mind that the US has a different system for rating hurricanes (Saffir-Simpson Scale) http://www.nhc.noaa.gov/sshws.shtml

Quote:
HURRICANE KATRINA ADVISORY NUMBER 25
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
10 PM CDT SUN AUG 28 2005

...POTENTIALLY CATASTROPHIC HURRICANE KATRINA CONTINUES TO APPROACH
THE NORTHERN GULF COAST...

A HURRICANE WARNING IS IN EFFECT FOR THE NORTH CENTRAL GULF COAST
FROM MORGAN CITY LOUISIANA EASTWARD TO THE ALABAMA/FLORIDA
BORDER...INCLUDING THE CITY OF NEW ORLEANS AND LAKE PONTCHARTRAIN.
PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO
COMPLETION.

A TROPICAL STORM WARNING AND A HURRICANE WATCH ARE IN EFFECT FROM
EAST OF THE ALABAMA/FLORIDA BORDER TO DESTIN FLORIDA...AND FROM
WEST OF MORGAN CITY TO INTRACOASTAL CITY LOUISIANA.

A TROPICAL STORM WARNING IS ALSO IN EFFECT FROM DESTIN FLORIDA
EASTWARD TO INDIAN PASS FLORIDA...AND FROM INTRACOASTAL CITY
LOUISIANA WESTWARD TO CAMERON LOUISIANA.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...INCLUDING POSSIBLE
INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR LOCAL WEATHER OFFICE.

AT 10 PM CDT...0300Z...THE CENTER OF HURRICANE KATRINA WAS LOCATED
NEAR LATITUDE 27.6 NORTH...LONGITUDE 89.4 WEST OR ABOUT 105 MILES
SOUTH OF THE MOUTH OF THE MISSISSIPPI RIVER AND ABOUT 170 MILES
SOUTH-SOUTHEAST OF NEW ORLEANS LOUISIANA.

KATRINA IS MOVING TOWARD THE NORTH-NORTHWEST NEAR 10 MPH...AND A
TURN TO THE NORTH IS EXPECTED OVER THE NEXT 12 TO 24 HOURS. ON THE
FORECAST TRACK THE CENTER OF THE HURRICANE WILL BE VERY NEAR THE
NORTHERN GULF COAST MONDAY MORNING. HOWEVER...CONDITIONS ARE
ALREADY DETERIORATING ALONG PORTIONS OF THE CENTRAL AND
NORTHEASTERN GULF COAST...AND WILL CONTINUE TO WORSEN THROUGH THE
NIGHT.

MAXIMUM SUSTAINED WINDS ARE NEAR 160 MPH WITH HIGHER GUSTS. KATRINA
IS A CATEGORY FIVE HURRICANE ON THE SAFFIR-SIMPSON SCALE. SOME
FLUCTUATIONS IN STRENGTH ARE LIKELY PRIOR TO LANDFALL...AND KATRINA
IS EXPECTED TO MAKE LANDFALL AT EITHER CATEGORY FOUR OR FIVE
INTENSITY. WINDS AFFECTING THE UPPER FLOORS OF HIGH-RISE BUILDINGS
WILL BE SIGNIFICANTLY STRONGER THAN THOSE NEAR GROUND LEVEL.

KATRINA REMAINS A VERY LARGE HURRICANE. HURRICANE FORCE WINDS EXTEND
OUTWARD UP TO 105 MILES FROM THE CENTER...AND TROPICAL STORM FORCE
WINDS EXTEND OUTWARD UP TO 230 MILES. A WIND GUST TO 90 MPH WAS
RECENTLY REPORTED FROM SOUTHWEST PASS LOUISIANA.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 904 MB...26.70 INCHES. AN
AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT WILL BE REACHING THE
CENTER OF KATRINA VERY SHORTLY.

COASTAL STORM SURGE FLOODING OF 18 TO 22 FEET ABOVE NORMAL TIDE
LEVELS...LOCALLY AS HIGH AS 28 FEET...ALONG WITH LARGE AND DANGEROUS
BATTERING WAVES...CAN BE EXPECTED NEAR AND TO THE EAST OF WHERE THE
CENTER MAKES LANDFALL. SOME LEVEES IN THE GREATER NEW ORLEANS AREA
COULD BE OVERTOPPED. SIGNIFICANT STORM SURGE FLOODING WILL OCCUR
ELSEWHERE ALONG THE CENTRAL AND NORTHEASTERN GULF OF MEXICO COAST.

RAINFALL TOTALS OF 5 TO 10 INCHES...WITH ISOLATED MAXIMUM AMOUNTS OF
15 INCHES...ARE POSSIBLE ALONG THE PATH OF KATRINA ACROSS THE GULF
COAST AND THE TENNESSEE VALLEY. RAINFALL TOTALS OF 4 TO 8 INCHES
ARE POSSIBLE ACROSS THE OHIO VALLEY INTO THE EASTERN GREAT LAKES
REGION TUESDAY AND WEDNESDAY.

ISOLATED TORNADOES WILL BE POSSIBLE THIS EVENING OVER SOUTHEASTERN
LOUISIANA...SOUTHERN MISSISSIPPI...SOUTHERN ALABAMA...AND OVER THE
FLORIDA PANHANDLE TONIGHT.

REPEATING THE 10 PM CDT POSITION...27.6 N... 89.4 W. MOVEMENT
TOWARD...NORTH-NORTHWEST NEAR 10 MPH. MAXIMUM SUSTAINED
WINDS...160 MPH. MINIMUM CENTRAL PRESSURE... 904 MB.

INTERMEDIATE ADVISORIES WILL BE ISSUED BY THE NATIONAL
HURRICANE CENTER AT MIDNIGHT CDT AND 2 AM CDT FOLLOWED
BY THE NEXT COMPLETE ADVISORY AT 4 AM CDT.

FORECASTER FRANKLIN


You will note that a Cat 5 in Australia is different to the SSS. See link below for a comparison:

http://www.bom.gov.au/cyclone/faq/index.shtml#definitions (Click on question #2)

To help people understand what a Cat 5 is capable of, the following is what a Cat 5 on the SSS can do:

Quote:
Category Five Hurricane (Sustained winds greater than 155 mph, greater than 135 kt, or greater than 249 km/hr).


Catastrophic damage will occur

People, livestock, and pets are at very high risk of injury or death from flying or falling debris, even if indoors in mobile homes or framed homes. Almost complete destruction of all mobile homes will occur, regardless of age or construction. A high percentage of frame homes will be destroyed, with total roof failure and wall collapse. Extensive damage to roof covers, windows, and doors will occur. Large amounts of windborne debris will be lofted into the air. Windborne debris damage will occur to nearly all unprotected windows and many protected windows. Significant damage to wood roof commercial buildings will occur due to loss of roof sheathing. Complete collapse of many older metal buildings can occur. Most unreinforced masonry walls will fail which can lead to the collapse of the buildings. A high percentage of industrial buildings and low-rise apartment buildings will be destroyed. Nearly all windows will be blown out of high-rise buildings resulting in falling glass, which will pose a threat for days to weeks after the storm. Nearly all commercial signage, fences, and canopies will be destroyed. Nearly all trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Long-term water shortages will increase human suffering. Most of the area will be uninhabitable for weeks or months. Hurricane Andrew (1992) is an example of a hurricane that brought Category 5 winds and impacts to coastal portions of Cutler Ridge, Florida with Category 4 conditions experienced elsewhere in south Miami-Dade County.


Yasi is now forecast to be the equivalent of a Cat 5 on the SSS. So, read what damge will occur and take the appropriate action all.
Posted by: Xavo

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:45

Rivers, this isn't the thread for general chat or asking those sorts of questions.
Take that to the General Discussion thread please.

Thankyou.
Posted by: 56craigl

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:49

Originally Posted By: Scud
Originally Posted By: dlcat1
Apologies if this isn't appropriate, but can anyone explain what I'm seeing with wind direction here at Willis Island? http://www.bom.gov.au/products/IDQ60801/IDQ60801.94299.shtml

I note the wind speed is still pretty much constant but the wind has appeared to swing through 180 degrees.

Is this just likely to be damage to the instrument or is there another explanation?

Cheers all.


Guessing here but I'd say that the winds are so strong and consistent that the wind direction vane has flipped 180 deg, and just can't flip back?

The latest radar image from Willis Is is from 10 minutes ago (2050 UTC time) which definitely shows the eye still to the east of the radar site. Winds shouldn't be from the north so my guess is there is something wrong with the equipment. I hope the readings aren't affected by it. The eye looks like it will pass right over the top, would be amazing to see the values coming out from it.
Posted by: Ree

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 08:55

TOP PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 12
Issued by the Bureau of Meteorology, Brisbane
Issued at 7:54am EST on Wednesday the 2nd of February 2011

A Cyclone WARNING is current for island and coastal areas from Cape Melville to
Sarina, extending inland to Croydon and Richmond.

A Cyclone WATCH is current for the remaining tropical interior east of Camooweal
and north of Winton.

At 7:00 am EST Severe Tropical Cyclone Yasi, Category 5 was estimated to be
555 kilometres east of Cairns and 560 kilometres northeast of Townsville
moving west southwest at 30 kilometres per hour.

SEVERE TC YASI IS A LARGE AND VERY POWERFUL TROPICAL CYCLONE AND POSES AN
EXTREMELY SERIOUS THREAT TO LIFE AND PROPERTY WITHIN THE WARNING AREA,
ESPECIALLY BETWEEN CAIRNS AND TOWNSVILLE.

THIS IMPACT IS LIKELY TO BE MORE LIFE THREATENING THAN ANY EXPERIENCED DURING
RECENT GENERATIONS.

TC Yasi, CATEGORY 5, will continue to move in a west-southwesterly direction
during the day. The cyclone is expected to cross the coast in the Innisfail area
at about midnight.

Coastal residents within the warning area, and particularly between Cairns and
Ayr are specifically warned of an EXTREMELY DANGEROUS SEA LEVEL RISE
[i.e. storm tide] as the cyclone approaches, crosses the coast and moves inland.
The sea is likely to steadily rise up to a level which will be VERY DANGEROUSLY
above the normal tide, with EXTREMELY DAMAGING WAVES, STRONG CURRENTS and
FLOODING of low-lying areas extending some way inland. People living in areas
likely to be affected by this flooding should take measures to protect their
property as much as possible, and be prepared to follow instructions regarding
evacuation of the area if advised to do so by authorities.

DAMAGING WINDS with gusts to 90 km/hr that are currently developing on coastal
islands, are forecast to develop about the coast by late morning and about the
tropical interior overnight.

Between Cape Tribulation and Ingham these winds will become DESTRUCTIVE with
gusts in excess of 125km/hr during the afternoon and early evening and VERY
DESTRUCTIVE with gusts up to 300 km/hr between Cairns and Ingham during the
evening as the cyclone approaches and crosses the coast. These VERY DESTRUCTIVE
winds can also occur on the seaward side of hills to the north of the cyclone
and are also forecast to reach the Atherton Tablelands.

Winds are forecast to ease about the east coast during Thursday morning as the
cyclone moves inland.

FLOODING RAINS will develop from Cooktown to Sarina during the afternoon and
then extend inland overnight.
People between Cape Melville and Sarina, extending inland to Croydon and
Richmond should complete preparations quickly and be prepared to shelter in a
safe place.
- Boats and outside property should be secured.
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

People about the remaining tropical interior east of Camooweal and north of
Winton should consider what action they will need to take if the cyclone threat
increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 7:00 am EST:
.Centre located near...... 16.1 degrees South 150.9 degrees East
.Location accuracy........ within 20 kilometres
.Recent movement.......... towards the west southwest at 30 kilometres per hour
.Wind gusts near centre... 295 kilometres per hour
.Severity category........ 5
.Central pressure......... 922 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 11:00 am EST Wednesday 02 February.

This warning is also available through TV and Radio Broadcasts; the Bureau's
website at www.bom.gov.au or call 1300 659 212. The Bureau and the State
Emergency Service would appreciate this warning being broadcast regularly.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 09:02

Originally Posted By: dlcat1
but can anyone explain what I'm seeing with wind direction here at Willis Island? I note the wind speed is still pretty much constant but the wind has appeared to swing through 180 degrees.

I've heard of this before. Part of the wind direction vane has probably broken off (the tail I'd guess) so now the head has become the tail.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 09:24

Eyewall is quite eroded on the latest microwave. Maps to the lack of precip and relative wind that Willis is reporting. This may relate to the deficit in OHC or it coul dbe something completely different.

Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 09:40

Well that's good news. The front eyewall is looking quite eroded - I wondered yesterday if it would be able to hold cat 5 with the lack of deep hot water - this may be bearing fruit. Of course it could well be temporary and certainly wont be reflected in the forecsts but theres a hint of a possibility that it might weaken a little. Hoping is the key word here.



Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 09:42

As ITN showed with the composite image above the eyewall does look quite eroded but I doubt it is due to the OHC. That might limit the intensity of the system, but I doubt it would impact the structure significantly.


The same thing is visible on the vis sat shot with a pretty poorly formed eye (in the NW quadrant), this despite the radar showing a solid eyewall


NOTE: these images are 3 hrs apart and so the similarity is coincidence only.

I'm not sure what could cause it, perhaps just an instability? Perhaps an injection of dry air (although that is not supported by the WV sat shots)
Posted by: weathermax

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 09:44

1 Tropical Cyclone Less than 125 km/h
Gales Minimal house damage. Damage to some crops, trees and caravans.Boats may drag moorings.
2 Tropical Cyclone 125 - 164 km/h
Destructive winds Minor house damage. Significant damage to signs, trees and caravans. Heavy damage to some crops. Risk of power failure. Small boats may break moorings.
3 Severe Tropical Cyclone 165 - 224 km/h
Very destructive winds Some roof and structural damage. Some caravans destroyed. Power failure likely.
4 Severe Tropical Cyclone 225 - 279 km/h
Very destructive winds Significant roofing and structural damage. Many caravans destroyed and blown away. Dangerous airborne debris. Widespread power failures.
5 Severe Tropical Cyclone More than 280 km/h
Extremely destructive winds Extremely dangerous with widespread destruction.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 09:49

I rang one of my weather mates (I'm not "in the know" for nothing!) amd asked why he thought it was so. He reckoned it could be due cold upwelling water that occurs on the poleward (southern) side of intense tropical cyclones. This occurs due to something called eddie defusion (sounds like a rock star) and where high sea surface temperatures overlay colder water.

As the winds sweep around the southern side they see this colder water and this decreases the amount of energy available to the western side of the system.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 09:53

Actually, I might have jumped the gun there.
Looking at the vis shot again, I'm not convinced that the "erosion" of the eye that you can see in the NE is actually anything other than perhaps some highlevel cloud?
Posted by: weathermax

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 09:56

It was just announced on sunrise that Willis Island weather station has just been destroyed, if this is the case - how do we get updates for YASI? Is there another way of monitoring besides Willis Island?
Posted by: Things

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 09:58

Only sat images now weathermax.

The instability in the eye wall is probably caused by Yasi's interaction with the coast.
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:00

Originally Posted By: weathermax
It was just announced on sunrise that Willis Island weather station has just been destroyed

A more reasonable assumption is that communications have been lost - but reasonable assumptions and the media do not coexist easily.

Satellite data every hour, radar data every 10 minutes at 300 km range (starting to see on Cairns radar as we speak), wind observations at Holmes Reef and Flinders every 30 minutes. Plenty of info.
Posted by: Spotted Reptile

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:00

Willis is still transmitting barometric and temp readings so far. The anemometer appears dead.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:00

Thanks ITN, interesting explanation ... I;d still be surprised if something like that could have a storm scale imapct on a cyclone of this size. THe eye is rotating at 150+km/h which means I would have thought any particular quater of the eye's residence time over any "cold eddy" would be too short for it to have any significnat impact.

Below is a levels modified version of the visible sat shot above, in an effort to see some of the CDO and eyewall features more clearly.

Posted by: Gustfront PD

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:01

Yasi has regestered gusts so far to 185km/h at Willis Island
Bom Weather Observations for Willis Island - Bom Willis Island Obs
Latest obs at 8-10am Sustained Wind speeds 141km/h Gusts to 185km/h
Posted by: teckert

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:08

Can we please keep the chat out of this thread thanks.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:18

Originally Posted By: Things
You can clearly see the East side of Yasi being deformed by the coast. Considering it's size, it's actually fairly close.
No I dont think that is what is affecting the eye, but it is an interesting hypothesis smile

The coast may be impacting some of the outer rain bands, but it is not likely to be having any discernible impact on the inner core of the cyclone yet. As I corrected earlier, the eye actually is not that bad. The MW image which showed a distorted eye was taken over 4 hours ago, and the latest IR shots show a reasonably symmetrical eyewall.
Posted by: TrenthamStormchasers

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:25

Clyve Herbert's TC Yasi discussion on our AUSSKY AUSTRALIAN REGION TROPICAL WEATHER BRIEF/CONVECTIVE NOTE is excerpted here with more information available at this link

http://www.stormchasers.au.com/current.htm


"TC YASI: Has strengthened to Cat 5 and now returns estimated pressure values below 920hPa, as the core passes across Willis Island and approaches the north QLD coast pressure may reach 900hPa, has developed strong upper divergence and very efficient low level convergence, a very pronounced eye feature has evolved, extreme wind gusts near the eye wall especially the western and southwestern quadrants may achieve 300kph today, weak concentric eye wall features appear on the northern quadrant.
The tracking of TC Yasi is towards 265/268 degrees, the expected tracking is favoured to be along a 260/280 degree course, the compression of the southeast surface flow against the coastal range between Cardwell and Mossman may induce a slightly more NW coarse this afternoon, for the Cairns region a favoured course would be to the south of the city allowing off shore severe winds, however if the core passes just north of the city a devastating north or northeast surface flow on the northern and NE quadrant may induce a phenomenal tidal response, also this tracking scenario may cause the strongest winds near the ye wall of the northeast quadrant to reach the city. "

Go here for more... http://www.stormchasers.au.com/current.htm
Posted by: Things

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:30

I have been wondering about the effects the coast will have on the movement. A NW movement as it hits could well and truly bring it into my area, however I don't have a clue as to the intensity of this movement if it happens. Did Larry experience a similar movement due to the coast?
Posted by: weathermax

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:36

WTPS31 PGTW 011500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 11P (YASI) WARNING NR 006//
RMKS/
1. TROPICAL CYCLONE 11P (YASI) WARNING NR 006
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
011200Z --- NEAR 14.9S 153.2E
MOVEMENT PAST SIX HOURS - 255 DEGREES AT 17 KTS
POSITION ACCURATE TO WITHIN 020 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT
100 NM SOUTHEAST QUADRANT
100 NM SOUTHWEST QUADRANT
090 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT
200 NM SOUTHEAST QUADRANT
200 NM SOUTHWEST QUADRANT
180 NM NORTHWEST QUADRANT
REPEAT POSIT: 14.9S 153.2E
---
FORECASTS:
12 HRS, VALID AT:
020000Z --- 15.9S 149.7E
MAX SUSTAINED WINDS - 130 KT, GUSTS 160 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 050 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 100 NM NORTHEAST QUADRANT
110 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT
210 NM SOUTHEAST QUADRANT
210 NM SOUTHWEST QUADRANT
190 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 250 DEG/ 18 KTS
---
24 HRS, VALID AT:
021200Z --- 17.1S 146.2E
MAX SUSTAINED WINDS - 130 KT, GUSTS 160 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 050 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 100 NM NORTHEAST QUADRANT
110 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT
210 NM SOUTHEAST QUADRANT
210 NM SOUTHWEST QUADRANT
190 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 245 DEG/ 17 KTS
---
36 HRS, VALID AT:
030000Z --- 18.5S 143.0E
MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 48 HR POSIT: 245 DEG/ 15 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
031200Z --- 19.7S 140.2E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 72 HR POSIT: 245 DEG/ 12 KTS
---
72 HRS, VALID AT:
041200Z --- 21.7S 135.6E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
011500Z POSITION NEAR 15.2S 152.3E.
TROPICAL CYCLONE (TC) 11P (YASI), LOCATED APPROXIMATELY 450 NM EAST-
NORTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD AT 17
KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY
SHOWS A 10 NM EYE, FROM WHICH THE INITIAL POSITION WAS BASED. THE
INITIAL INTENSITY WAS BASED ON PGTW AND ABRF DVORAK ESTIMATES
RANGING FROM 115 TO 127 KNOTS. A POLEWARD OUTFLOW CHANNEL INTO AN
UPPER LEVEL LOW TO THE SOUTH, ALONG WITH GOOD EQUATORWARD OUTFLOW
HAS ALLOWED FOR RAPID INTENSIFICATION WITHIN THE PAST 12 HOURS. TC
11P IS CURRENTLY TRACKING ALONG THE NORTHERN PERIPHERY OF A DEEP
LAYER SUBTROPICAL STEERING RIDGE AND IS EXPECTED TO TRACK GENERALLY
WEST-SOUTHWESTWARD THROUGHOUT THE FORECAST PERIOD. THE SYSTEM SHOULD
CONTINUE TO INTENSIFY DUE TO EXCELLENT OUTFLOW, LOW VERTICAL WIND
SHEAR, AND FAVORABLE OCEANIC CONDITIONS. AROUND TAU 24, THE SYSTEM
IS FORECAST TO MAKE LANDFALL JUST SOUTH OF CAIRNS AND BEGIN
WEAKENING AS IT TRACKS INLAND. THE AVAILABLE NUMERICAL MODEL
GUIDANCE IS IN TIGHT AGREEMENT AND TRACK CONFIDENCE IS HIGH.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 011200Z IS 38 FEET. NEXT WARNINGS
AT 020300Z AND 021500Z.//
NNNN
Posted by: weathermax

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:41



Latest Image from JTWC
Posted by: jdh

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:42

Hi guys, in my opinion vertical shear is much more likely to be the reason for the weaker western eyewall than anything to do with the sea surface. AMSU passes indicate that the system is currently in an environment of around 15 to 20 knots of 850-200 hPa northerly vertical shear. This would favour upmotion and deep convection in the downshear direction (i.e. the eastern quadrants), and subsidence and supression of deep convection in the western quadrants. Note that most of the penetrating deep convective tops in opplevelse's vis image are in the eastern semi-circle. The rainfall max and dense high level overcast on the western side would be the result of hydrometeors being rapidly advected from the more active eastern flank by the cyclonic circulation.
Posted by: Pacman

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:42

Originally Posted By: TrenthamStormchasers
Clyve Herbert's TC Yasi discussion on our AUSSKY AUSTRALIAN REGION TROPICAL WEATHER BRIEF/CONVECTIVE NOTE is excerpted here with more information available at this link

http://www.stormchasers.au.com/current.htm


"TC YASI: Has strengthened to Cat 5 and now returns estimated pressure values below 920hPa, as the core passes across Willis Island and approaches the north QLD coast pressure may reach 900hPa, has developed strong upper divergence and very efficient low level convergence, a very pronounced eye feature has evolved, extreme wind gusts near the eye wall especially the western and southwestern quadrants may achieve 300kph today, weak concentric eye wall features appear on the northern quadrant.
The tracking of TC Yasi is towards 265/268 degrees, the expected tracking is favoured to be along a 260/280 degree course, the compression of the southeast surface flow against the coastal range between Cardwell and Mossman may induce a slightly more NW coarse this afternoon, for the Cairns region a favoured course would be to the south of the city allowing off shore severe winds, however if the core passes just north of the city a devastating north or northeast surface flow on the northern and NE quadrant may induce a phenomenal tidal response, also this tracking scenario may cause the strongest winds near the ye wall of the northeast quadrant to reach the city. "

Go here for more... http://www.stormchasers.au.com/current.htm


Wow that could bring us back into the firing line for sure, wonder if the BOM are on this??
Posted by: He who once was ITN

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 10:53

Hi jdh - interesting hypothesis but not supported by analysed wind shear - which could be wrong of course

Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 11:00

This is the latest Vis shot modified like the one before ... just for [censored] and giggles.
Posted by: Seina

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 11:03

I don’t think this is the time for speculation, but I did a latitudinal check on the likely region(s) to be affected (mean sea level pressure and rainfall) and it seems that between 18 and 20 deg South and 146 and 148 East there is going to be some serious weather on the way.

However, please do not take this to be anything more than theoretical, even though it’s less than a day out, this thing is bloody huge!
Posted by: jdh

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 11:14

A time series of the AMSU estimated wind shear can be found here:

http://rammb.cira.colostate.edu/products...00000000000.GIF

This is an area average over a 600 km radius centred on the cyclone using a balanced 3-D wind field computed from the AMSU temperature retrievals.

Yes, this does disagree with the CIMMS product, which is a model (GFS) optimised product based on observed cloud drift winds. In this case it seems to me that the AMSU data fit the obs a lot better.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 11:17

I have no idea what a latitudinal check is, but it sure sounds impressive! Can you explain what you mean? wink
Posted by: Seina

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 11:27

Originally Posted By: opplevelse
I have no idea what a latitudinal check is, but it sure sounds impressive! Can you explain what you mean? wink

Go to here: http://nomad3.ncep.noaa.gov/cgi-bin/pdisp_gfs_dir.sh?dir=%2Fgfs20110201

gfs_18z.ctl GFS fcst starting from 18Z01feb2011, downloaded Feb 01 22:32 UTC

Single variable

Lat/lon vs. time

Variable: PRATE, or any.

Convert to 86400 seconds (extra operation)

Select latitude range

Plot
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 11:31

Centre of the eye seems to have passed Willis is with a pressure down to 937.6hPa
Posted by: Scottie A

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 11:46

Geeze this looks like a very intense cyclone... im quite stunned and lost for words, so ill just post a few charts... here is the latest 0014 IR Colour MTSAT Image.



and BD

Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 12:03

Latest MW shot still shows a "hole" in the eyewall, albeit rotated. THis one was about 3 hrs ago

and about 3 hrs after the last.
Posted by: LittleDavey83

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 12:12

IDQ20018
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - EASTERN REGION
Issued by BRISBANE TROPICAL CYCLONE WARNING CENTRE
at: 0107 UTC 02/02/2011
Name: Severe Tropical Cyclone Yasi
Identifier: 14U
Data At: 0000 UTC
Latitude: 16.4S
Longitude: 149.9E
Location Accuracy: within 15 nm [30 km]
Movement Towards: west southwest [248 deg]
Speed of Movement: 19 knots [35 km/h]
Maximum 10-Minute Wind: 115 knots [215 km/h]
Maximum 3-Second Wind Gust: 160 knots [295 km/h]
Central Pressure: 922 hPa
Radius of 34-knot winds NE quadrant: 190 nm [350 km]
Radius of 34-knot winds SE quadrant: 250 nm [465 km]
Radius of 34-knot winds SW quadrant: 260 nm [480 km]
Radius of 34-knot winds NW quadrant: 190 nm [350 km]
Radius of 48-knot winds NE quadrant: 90 nm [165 km]
Radius of 48-knot winds SE quadrant: 130 nm [240 km]
Radius of 48-knot winds SW quadrant: 130 nm [240 km]
Radius of 48-knot winds NW quadrant: 60 nm [110 km]
Radius of 64-knot winds: 40 nm [70 km]
Radius of Maximum Winds: 15 nm [30 km]
Dvorak Intensity Code: T6.0/6.5/D1.0/24HRS STT:S0.0/6HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 240 nm [445 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 02/1200: 17.6S 146.5E: 045 [085]: 115 [215]: 922
+24: 03/0000: 18.9S 143.2E: 075 [140]: 050 [095]: 976
+36: 03/1200: 20.1S 140.3E: 110 [205]: 030 [055]: 990
+48: 04/0000: 21.2S 137.8E: 140 [260]: 025 [045]: 999
+60: 04/1200: 22.1S 135.8E: 185 [345]: 025 [045]: 998
+72: 05/0000: 23.0S 134.6E: 230 [425]: 025 [045]: 996
REMARKS:
Following a period of rapid intensification overnight to category 5 intensity,
Yasi has possibly steadied in the past 6 hours. Dvorak intensity: Eye pattern
that had been based on W surround [6.0]and OW/W eye [0.5] adjustment has
weakened to an LG surround [5.0] and OW/W [0.5]. Nevertheless time averaged DT
is 6.0 and MET also at 6.0. CI held at 6.5. Max winds estimated at 115 knots
supported by AMSU/SATCON estimates at 125kn [1min], although Willis Island
pressure observations suggest a slightly weaker system.

The intensity is maintained through to landfall, given the environment of low
shear and strong upper level outflow.

Motion remains steady west southwest at 18 knots which should persist through to
landfall.

The combination of being intense, larger than normal [gales extending about
250nm to the south] and the 18 knot motion is enhancing waves/swell and the
storm tide potential. Much depends upon the timing of landfall [high tide is
about 21:00EST] as to the overall tide impact which potentiall is significant.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 02/0700 UTC by Brisbane
TCWC.
Posted by: Doomadgee

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 12:19

Advice number 13 is out now

http://www.bom.gov.au/cgi-bin/wrap_fwo.pl?IDQP0005.txt

Details of Severe Tropical Cyclone Yasi at 10:00 am EST:
.Centre located near...... 16.4 degrees South 149.9 degrees East
.Location accuracy........ within 30 kilometres
.Recent movement.......... towards the west southwest at 30 kilometres per hour
.Wind gusts near centre... 295 kilometres per hour
.Severity category........ 5
.Central pressure......... 922 hectoPascals
Posted by: !SCHUMMY!

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 12:20

here is STC YASI's position with what UKMET/GFS were/are predicting where she will go. There is a vis image overlayed to give a better idea....



Forecast winds are expected to be 130knots sustained according to CIMSS

Quote:
Following a period of rapid intensification overnight to category 5 intensity,
Yasi has possibly steadied in the past 6 hours. Dvorak intensity: Eye pattern
that had been based on W surround [6.0]and OW/W eye [0.5] adjustment has
weakened to an LG surround [5.0] and OW/W [0.5]. Nevertheless time averaged DT
is 6.0 and MET also at 6.0. CI held at 6.5. Max winds estimated at 115 knots
supported by AMSU/SATCON estimates at 125kn [1min], although Willis Island
pressure observations suggest a slightly weaker system.
Posted by: Tempest

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 12:45

BOM's latest track now has it crossing south of Innisfail
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 12:49

That is great news for Inniosfail, but bad news for cardwell where the storm surge could really be funnelled.

Eye is just coming back into view on the Cairns 512km comp
Posted by: Inclement Weather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 13:11

Thanks for your imput Jonty, always good to hear from you on the forum. At the risk of 'chat', I hope things are well for you in the States. On the queston of shear, the latest shear chart indicates a marginal strengthening of shear as it nears the coast. However, it is marginal and of little comfort in having this system weaken much before crossing. It can only be hoped, as I have previously indicated, that becasue of its sheer size, interaction with the land can weaken it a little still. No matter what, I fear the worse.
Posted by: MikeM

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 13:23

The wind recordings for willis island have dissappeared. The last recording was at about 185 km/h before the eye, this is not indicative of the strength they say it is. But all the wind data is gone ????
Posted by: point breaks

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 13:44

Originally Posted By: MikeM
The wind recordings for willis island have dissappeared. The last recording was at about 185 km/h before the eye, this is not indicative of the strength they say it is. But all the wind data is gone ????


If you are looking for wind reports from Willis, I was posting one every half hour until failure for most of early hours this morning I think, in the other thread

Apologies, I would search and post them myself, but am at work and dead tired.
Posted by: windjammer

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 13:47

I have just seen a BoM spokesman interviewed on t.v, and he said at this stage they are unsure what has happened damage-wise to the Willis island station.

However, he stated that it was built to withstand a cat 5 system, and allowed that it has potentially been destroyed.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 13:57

There was a Terra image this morning but it was right at the edge of frame so the resolution is not great and it is distorted:
http://rapidfire.sci.gsfc.nasa.gov/realtime/single.php?T110330045

There could be a slightly better one in an hour or so (Scan starts about 03:30Z), but again, I suspect (judging by the satellite track) it will be a bit to the edge of frame frown So unfortunately it looks like there will not be any good moderate resolution visible images of the eye as the rest of the passes for Aqua and Terra are going to be later at night.
Posted by: HermSherm

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 14:27



I have calculated using JTWC data HSI values (size, intensity) of 34 (17,17.3) currently and 36 (17,18.8) for 9pm EST you can compare these at www.impactweather.com noting Hurricane Katrina was a 36 (23,13) at landfall and Hurricane Camille 36 (14,22) at landfall.

From JTWC:

WTPS31 PGTW 020300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 11P (YASI) WARNING NR 007//
RMKS/
1. TROPICAL CYCLONE 11P (YASI) WARNING NR 007
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
020000Z --- NEAR 16.4S 149.9E
MOVEMENT PAST SIX HOURS - 245 DEGREES AT 16 KTS
POSITION ACCURATE TO WITHIN 030 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 125 KT, GUSTS 150 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 085 NM NORTHEAST QUADRANT
095 NM SOUTHEAST QUADRANT
085 NM SOUTHWEST QUADRANT
080 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 200 NM NORTHEAST QUADRANT
220 NM SOUTHEAST QUADRANT
200 NM SOUTHWEST QUADRANT
190 NM NORTHWEST QUADRANT
REPEAT POSIT: 16.4S 149.9E
---
FORECASTS:
12 HRS, VALID AT:
021200Z --- 17.7S 146.6E
MAX SUSTAINED WINDS - 130 KT, GUSTS 160 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 090 NM NORTHEAST QUADRANT
100 NM SOUTHEAST QUADRANT
090 NM SOUTHWEST QUADRANT
090 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT
200 NM SOUTHEAST QUADRANT
180 NM SOUTHWEST QUADRANT
180 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 245 DEG/ 18 KTS
---
24 HRS, VALID AT:
030000Z --- 19.2S 143.1E
MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 36 HR POSIT: 240 DEG/ 17 KTS
---
36 HRS, VALID AT:
031200Z --- 20.9S 140.0E
MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 48 HR POSIT: 230 DEG/ 14 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
040000Z --- 22.6S 137.6E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
020300Z POSITION NEAR 16.7S 149.1E.
TROPICAL CYCLONE (TC) 11P (YASI), LOCATED APPROXIMATELY 245 NM EAST
OF CAIRNS, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD AT 16 KNOTS
OVER THE PAST SIX HOURS. THE TC TRACKED OVER WILLIS ISLAND AT AROUND
2200Z WITH MAXIMUM SUSTAINED WINDS LOGGED IN EXCESS OF 70 KNOTS
GUSTING TO OVER 100 KNOTS. AN IMPRESSIVE EYEWALL HAD BEEN VISIBLE ON
THE WILLIS ISLAND RADAR THAT HAS SINCE BECOME INOPERABLE. THE
CYCLONE WILL MOVE WITHIN RANGE OF THE CAIRNS RADAR IN THE NEXT FEW
HOURS AND WILL PASS BETWEEN HOLMES REEF AND FLINDERS REEF BEFORE
MAKING LANDFALL NEAR CAIRNS. THE TC SHOULD MAINTAIN ITS CURRENT
INTENSITY OF 125 KNOTS (OR POSSIBLY EVEN STRENGTHEN SOME) BEFORE
MAKING LANDFALL AS ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE.
DVORAK ESTIMATES FROM PGTW AND ABRF CURRENTLY RANGE FROM 115 TO 127
KNOTS. YASI WILL DISSIPATE OVER THE INTERIOR OF AUSTRALIA AFTER
COMING ASHORE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 020000Z IS 38 FEET.
NEXT WARNINGS AT 021500Z AND 030300Z.//
NNNN
Posted by: cyclonecece

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 14:54

IDQP0005
Australian Government Bureau of Meteorology
Queensland
Tropical Cyclone Warning Centre

Media: Transmitters serving the area from Cape Flattery to Sarina and inland to
Georgetown are requested to USE the Standard Emergency Warning Signal before
broadcasting the following warning.

TOP PRIORITY
TROPICAL CYCLONE ADVICE NUMBER 14
Issued by the Bureau of Meteorology, Brisbane
Issued at 1:53pm EST on Wednesday the 2nd of February 2011

A Cyclone WARNING is current for coastal and island communities from Cape
Flattery to Sarina, extending inland to Julia Creek and to the area west of
Croydon.

A Cyclone WATCH is current for the remaining inland parts west to the Northern
Territory border and north of Winton.

The Cyclone WARNING from Cape Melville to Cape Flattery has been cancelled.

At 1:00 pm EST Severe Tropical Cyclone Yasi, Category 5 was estimated to be 345
kilometres east of Cairns and 360 kilometres northeast of Townsville and moving
west southwest at 35 kilometres per hour.

SEVERE TROPICAL CYCLONE YASI IS A LARGE AND VERY POWERFUL TROPICAL CYCLONE AND
POSES AN EXTREMELY SERIOUS THREAT TO LIFE AND PROPERTY WITHIN THE WARNING AREA,
ESPECIALLY BETWEEN CAIRNS AND TOWNSVILLE.

DURING THE EVENING, THE VERY DESTRUCTIVE CORE OF CYCLONE YASI WILL CROSS THE
COAST BETWEEN CAIRNS AND INGHAM, ACCOMPANIED BY A DANGEROUS STORM TIDE SOUTH OF
THE CYCLONE CENTRE.

Tropical Cyclone Yasi, CATEGORY 5, will continue to move in a west-southwesterly
direction. The cyclone is expected to cross the coast between Innisfail and
Cardwell close to midnight.

Coastal residents within the warning area, and particularly between Cairns and
Proserpine including the Whitsundays, are specifically warned of an EXTREMELY
DANGEROUS SEA LEVEL RISE [i.e. storm tide] as the cyclone approaches, crosses
the coast and moves inland. The sea is likely to steadily rise up to a level
which will be VERY DANGEROUSLY above the normal tide, with EXTREMELY DAMAGING
WAVES, STRONG CURRENTS and FLOODING of low-lying areas extending some way
inland. People living in areas likely to be affected by this flooding should
take measures to protect their property as much as possible, and be prepared to
follow instructions regarding evacuation of the area if advised to do so by
authorities.

DAMAGING WINDS with gusts to 90 km/hr are currently affecting the coast and
islands, and are forecast to spread into the tropical interior overnight and
west to Julia Creek during Thursday.

Between Port Douglas and Ayr these winds will become DESTRUCTIVE with gusts in
excess of 125 km/hr developing during this afternoon and early evening,
spreading into the tropical interior overnight. VERY DESTRUCTIVE winds with
gusts up to 290 km/hr are expected to develop between Cairns and Ingham during
the evening as the cyclone approaches and crosses the coast. These VERY
DESTRUCTIVE winds will also occur on the seaward side of hills to the north of
the cyclone and also affect the Atherton Tablelands.

Due to the large size of the cyclone, people in the path of the VERY DESTRUCTIVE
WINDS are likely to experience these conditions for about 3 to 4 hours.

Winds are forecast to gradually ease about the east coast during Thursday
morning as the cyclone moves inland.

FLOODING RAINS will develop from Cooktown to Sarina during the afternoon and
then extend inland overnight.

People between Cape Flattery and Sarina, extending inland to Julia Creek and to
the area west of Croydon should complete preparations quickly and be prepared to
shelter in a safe place.
- Boats and outside property should be secured.
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

People about the remaining inland parts west to the Northern Territory border
and north of Winton should consider what action they will need to take if the
cyclone threat increases.
- Information is available from your local government
- For cyclone preparedness and safety advice, visit Queensland's Disaster
Management Services website [www.disaster.qld.gov.au]
- For emergency assistance call the Queensland State Emergency Service [SES] on
132 500 [for assistance with storm damage, rising flood water, fallen trees on
buildings or roof damage].

Details of Severe Tropical Cyclone Yasi at 1:00 pm EST:
.Centre located near...... 16.8 degrees South 149.0 degrees East
.Location accuracy........ within 30 kilometres
.Recent movement.......... towards the west southwest at 35 kilometres per hour
.Wind gusts near centre... 290 kilometres per hour
.Severity category........ 5
.Central pressure......... 930 hectoPascals


Please ensure that neighbours have heard and understood this message,
particularly new arrivals or those who may not fully understand English.

The next advice will be issued by 3:00 pm EST Wednesday 02 February.

This warning is also available through TV and Radio Broadcasts; the Bureau's
website at www.bom.gov.au or call 1300 659 212. The Bureau and the State
Emergency Service would appreciate this warning being broadcast regularly.
Posted by: Learjet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 15:13

2pm NOAA 19 pass from 137.100 mHz VHF.

Position roughly 460km at 353 degrees from Mackay (red +)

IR.



Visible.

Posted by: cumulofloodus

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 15:18

Graph of Flinders Reef data so far ...
Posted by: cumulofloodus

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 15:30

Graph of Willis Island up until the station died. That's the only data range I copied into the spreadsheet before the wind speed columns were blanked out.
Posted by: Mike M

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 16:11

Just noticed something strange - Willis Island bottomed out at 938hpa and measured winds of 185km/hr before it got taken out. There are now TWO other AWS's within a close vicinity of the eye wall (Holmes and Flinders Reef) stations. They're both within 60km of it and are measuring pressures of "only" 976hpa and wind gusts to 158? For a cat 5 system that's so large, something isn't adding up? Perhaps we won't see the super destructive winds mentioned?

Cheers, Mike
Posted by: !SCHUMMY!

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 16:13

Details of Severe Tropical Cyclone Yasi at 3:00 pm EST:
.Centre located near...... 17.0 degrees South 148.4 degrees East
.Location accuracy........ within 30 kilometres
.Recent movement.......... towards the west southwest at 35 kilometres per hour
.Wind gusts near centre... 285 kilometres per hour
.Severity category........ 5
.Central pressure......... 930 hectoPascals

shes a borderline CAT4/5 now, might go through one more EWR at landfall which should weaken her....?
Posted by: Seina

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 16:14

I am not sure where to put this, so any advice would be welcome:

I can understand the desire to understand the events in Queensland…but I must add that I feel this system (Severe TC Yasi) represents something quite nasty for the communities expected to be affected…if what the experts are saying turns out that way.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 16:15

Ok the Aqua full scan that I mentioned earlier, and as suspected the cyclone is right at the edge of the scan frown
This is the raw data so the scan lines have not been merged, but you can still make out the eye clearly, and some of the internal structure.

*Click on the image for MASSIVE 250m resolution version*


Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 16:19

And this is a crop of the eye from the full sized version of the aqua image above ... each pixel = 250m.

I've adjusted the levels to enhance features

Posted by: Things

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 16:25

Can someone have a look at the 6 hour weatherzone radar, set it on fastest and give me your opinion on where it is heading? Almost looks to have taken a completely due West track.

EDIT: OOp, this was probably the wrong thread.
Posted by: Popeye

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 16:47

Almost looks like Mission Beach area to me Things. Bugger.

ALSO what are peoples thoughts with this.

If BOMS High Seas Forecast of phenominal seas around the centre is correct then waves up to 14 metres could have been experienced at Willis island prior to the Automated weather station stopping transmitting. If the standard height is 10metres (?) above sea level for these instruments then by the looks of the lay of the land Willis island may have been completey 'washed over with water' I would be questioning the readings from there as the definate lowest hpa readings.

Edit: It might also explain why the BOM said willis would stand up to a CAT 5 but did they take into consideration the entire island and equipment being 'surged' over.

A very timely evacuation of the staff on the island yesterday I think.

definition from BOMS website. Phenomenal - over 14m - Precipitous seas (experienced only in cyclones)


Posted by: crikey

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 16:51

mmmm.
The data from the Islands has not updated for nearlytwo hours. None of them. Why??///
Is that queensland time l am in Vic
Maybe the server is busy?
http://www.bom.gov.au/qld/observations/qldall.shtml
The lasts stats were at 3.00pm It is 4:50pm in Victoria.
Posted by: Popeye

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 17:06

I stand corrected: Willis island is 9 metres above sea level. If only the results and AWS stood up to Yasi. It would have had the perfect 'hit' and set of information. Lets hope there is a glitch in the system. I doubt it though. OBS also had the apparent temperature jump from 5.6 to 32.6 degrees (sea water??)

Posted by: redbucket

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 17:10

Originally Posted By: Popeye
OBS also had the apparent temperature jump from 5.6 to 32.6 degrees (sea water??)


The wind obs stopped at the same time as the temp jumped so the apparent temperature calculations are incorrect.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 17:34

New MW image - 3hrs ago


Still showing this strange "hole" for want of a better term in the eyewall to the north whcih is not reflected in any other products (Vis / IR / Radar)? I wonder if it may be that the bulk motion of the storm (and it is moving fast) is deflecting the convection such that it is not reflecting strongly? Thoughts?

Actually looks almost like concentric eyewalls ...
Posted by: Inclement Weather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 17:39

Concentric eyewalls is not out the realm of possibility.
Posted by: Learjet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 17:45

4:30pm NOAA 15 pass taken from Mackay.

Position is roughly 455km at 342 degrees.

IR.



Visible.

Posted by: Inclement Weather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 18:10

The last few images on the radar loop are showing Yasi's eye looking a little elongated and ragged. It may be undergoing EWR, which will weaken it. With interaction with the land, mercifully it may drop to Cat 4 prior to landfall. We can be grateful for small mercies. Still, it will be devastating.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 18:25

Ok now the corrected version of the aqua shot has come out, I've modified the levels slightly to bring out the detail around the eye better.

At work so dont have PS to do it properly so this will have to do.

The original 250m version is here http://www.nrlmry.navy.mil/tcdat/tc11/SH...1499E.100pc.jpg

Click for much larger version


Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 19:04

Radar loop over the last 6hrs implying a track slightly north of the BoM's last map, putting an eye crossing at Innisfail later tonight.

CDO has expanded considerably in the last 2 hours, and this will be one of the last Visible images of Yasi, so I post it for posterity.
Posted by: MareebaWeather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 19:45

Originally Posted By: Cyclone
Online scanner feeds from Far North Queensland
RadioReference Feeds

---------------------------

Cyclone

Live Weather Data & Lightning Tracker



update to the above feeds:
Cairns police will go offline, during power failure.
I moved Cairns Police with Firecom ( backup power)


---------------------------

Cyclone

Live Weather Data & Lightning Tracker from Mareeba
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 19:46

Originally Posted By: E-J
Nothing Ragged about the eyewall at all. This thing will maintain intensity until landfall
Where did anyone say there was anything ragged about the eye? It looks perfectly symetrical at the moment.

It appears to have slowed down slightly. According to the radar it has averaged 22km/h over the last 2hrs. Current track has the western edge of the eye-wall about 150km from the coast which puts an eyewall crossing just North of Innisfail just after 1am local time.
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 20:17

Latest MW shot is much more symmetrical and appears much more intense than the previous one. This was taken about 1.5hrs ago.

Posted by: TC Poncho

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 20:54

from CIMSS


CIMSS TROPICAL CYCLONE INTENSITY CONSENSUS FOR 11P
CURRENT ESTIMATE
Date (yyyymmddhh): 2011020206
SATCON (2mem): MSLP = 911 hPa MSW = 135 kt
ADT: 903 hPa 137 kt Scene: EYE
CIMSS AMSU: 925 hPa 128 kt Bias Corr: -6 (MW)
CIRA AMSU: NA hPa NA kt Tmax: NA
Posted by: jss

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 22:08

Eyewall currently show a stable triangle mesovortex configuration. Crtical for near eyewall surge forecasts. Last frame also shows signs of a fourth vortex occuring. Vortex waves also very tightly wound around a tighening eyewall. Not sure when/if a replacement cyclone will occur before landfall.

Posted by: jss

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 02/02/2011 22:16

Concering the 16:29 post...

Thats a very beautiful eyewall opplevelse! There's plently of vorticity and eyewall wind jets crossing the eye and it appears to have a distinct triangle shape, hard to check without radar at this time. You've also got some nice horizontal rolls forming parallel to the vorticity gradient too!
Posted by: Adam Ant

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 10:02

Here is the radar from last night. You can really see the late SW movement that put Tully and Cardwell in the firing line

Cairns Radar 256km archive
Posted by: weathermax

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 10:47

What is the chance of this system reintensifying and move back east the same way Hurrican Katrina did? I notice this morning there is a low in WA moving east?
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 11:11

Originally Posted By: weathermax
What is the chance of this system reintensifying and move back east the same way Hurrican Katrina did? I notice this morning there is a low in WA moving east?
I would say none.

A few final images from last night while the forums were down. These first ones are IR shots with slightly modified levels to show up the structure better.

From 1232Z - 10:32pm AEST last night ~1:10hr before landfall


From 13:32Z - 11:32pm AEST last night ~0:10hr before landfall

And the multi


From 07:50Z - 5:50pm AEST last night. Note in particular the banding structure in the composite shot ... beautiful structure ... did someone say Vortex Rosby Waves?

And a recent MW Shot showing it still has pretty decent structure even well over land!
Posted by: Island viewer

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 11:17

Originally Posted By: opplevelse
Originally Posted By: weathermax
What is the chance of this system reintensifying and move back east the same way Hurrican Katrina did? I notice this morning there is a low in WA moving east?
I would say none.

A few final images from last night while the forums were down. These first ones are IR shots with slightly modified levels to show up the structure better.

From 1232Z - 10:32pm AEST last night ~1:10hr before landfall


From 13:32Z - 11:32pm AEST last night ~0:10hr before landfall
No chance of a dip into the Gulf either I trust
And the multi

From 07:50Z - 5:50pm AEST last night. Note in particular the banding structure in the composite shot ... beautiful structure ... did someone say Vortex Rosby Waves?
Posted by: Island viewer

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 11:19

Sorry, my post got lost with all the data,
I just wanted confirmation that a dip into the Gulf was also out of the question.
Posted by: weatherprincess

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 12:02

hello everyone i am a newbie, i have been watching the forums for a while, My heart is with everyone affect by this cyclone.

(now please dont bite my head off) - I am not a professional just someone that is interested in our weather system at present.

Would anyone be able to tell me what lies a head for QLD, i have been reading alot that there is a tropical low forming again that is likely to form into a cyclone? is that correct.

I am trying to understand the weather maps if there is a high does that mean you are safe from a cyclone?
Posted by: HermSherm

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 12:14

I couldn't get on last night however by this calculation before landfall based on JWTC data I underestimated the storm HSI prediction from yesterday.
HSI 40 intesity 20.25 size 20 wonder what it was at landfall

en.wikipedia.org/wiki/Hurricane_Severity_Index

Comparisons to US Hurricanes can be made here


[url=http://impactweather.com/HSI.pdf]


Some Comparable Hurricanes at landfall HSI (intensity,size) ranked out of 50

1961 Carla = 42(17,25)
1989 Hugo = 40(16,24)
1965 Betsy = 40(15,25)
1969 Camille = 36(22,14)
2005 Katrina = 36(13,23)
1926 Miami = 34(15,19)
2005 Wilma = 33(12,21)
1992 Andrew = 31(23,8)


From JWTC

WTPS31 PGTW 021500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 11P (YASI) WARNING NR 008//
RMKS/
1. TROPICAL CYCLONE 11P (YASI) WARNING NR 008
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
021200Z --- NEAR 17.5S 146.8E
MOVEMENT PAST SIX HOURS - 250 DEGREES AT 13 KTS
POSITION ACCURATE TO WITHIN 020 NM
POSITION BASED ON EYE FIXED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 135 KT, GUSTS 165 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 080 NM NORTHEAST QUADRANT
075 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 125 NM NORTHEAST QUADRANT
125 NM SOUTHEAST QUADRANT
115 NM SOUTHWEST QUADRANT
125 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 210 NM NORTHEAST QUADRANT
220 NM SOUTHEAST QUADRANT
200 NM SOUTHWEST QUADRANT
200 NM NORTHWEST QUADRANT
REPEAT POSIT: 17.5S 146.8E
---
FORECASTS:
12 HRS, VALID AT:
030000Z --- 18.6S 143.6E
MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 24 HR POSIT: 245 DEG/ 16 KTS
---
24 HRS, VALID AT:
031200Z --- 19.9S 140.4E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 36 HR POSIT: 240 DEG/ 13 KTS
---
36 HRS, VALID AT:
040000Z --- 21.1S 137.9E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
021500Z POSITION NEAR 17.8S 146.0E.
TROPICAL CYCLONE (TC) 11P (YASI), LOCATED APPROXIMATELY 70 NM EAST-
SOUTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD AT 13
KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY
SHOWS A 30 NM EYE AND THE CAIRNS RADAR DEPICTS A WELL-DEFINED
EYEWALL. THE INITIAL INTENSITY WAS BASED ON PGTW, KNES, AND ABRF
DVORAK ESTIMATES RANGING FROM 127 TO 140 KNOTS. TC 11P HAS SLIGHTLY
SLOWED IN TRANSLATION SPEED ALONG THE NORTHERN PERIPHERY OF A DEEP
LAYER SUBTROPICAL STEERING RIDGE AND IS EXPECTED TO MAKE LANDFALL
SOUTH OF CAIRNS WITHIN THE NEXT 6 HOURS. THE SYSTEM WILL BEGIN TO
WEAKEN AS IT TRACKS OVER LAND AND DISSIPATE AS A SIGNIFICANT
TROPICAL CYCLONE BY TAU 36. NUMERICAL MODEL FORECAST GUIDANCE IS IN
VERY GOOD AGREEMENT, THEREFORE THERE IS HIGH CONFIDENCE IN THIS
TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 021200Z IS 42
FEET. NEXT WARNINGS AT 030300Z AND 031500Z.//
NNNN
Posted by: weatherprincess

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 15:23

Question for someone:-
with cyclone yasi been so far inland it there a chance she instead of going into the NT it will stay in QLD and travel south?

Also with a cyclone being so far inland is there a chance of it turning in a tornado? sorry for the questions just new to the weather and worried for people up there
Posted by: jss

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 16:08

Yep, a nice vortex rossby wave and second eyewall in the northern section. Obs of 930hPa in eye too! 85GHz shows a tightening of tc just after landfall. Maybe diural?

Prior : http://tinyurl.com/65l9tp9

Post : http://tinyurl.com/6j7xww8
Posted by: weatherprincess

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 16:39

sorry Uq-wx i didnt quite understand your post could you explain
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 17:39

Unfortunately radar coverage is non existant where Yasi is, however the sat shots give a good idea where it is.

Tracking dead towards Mount Isa at the moment with a suprisingly good structure still

This is the weak MW range image from TRMM about 3hrs ago (3:38Z)



and the visible image shows just how much structure Yasi has maintained




Worthwhile monitoring Mt Isa over the next 12hrs. Yasi is still moving WSW at about 22km/h acording to the satellite map which puts it about 10hrs or so out of Mt Isa ... Given the LLCC is still 220km away from Mt Isa, it is still generating some pretty windy conditions!

This will update
Posted by: Surly Bond

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 17:47

Am I right in thinking that this event has left practically no instrumental records of hurricane-force winds or extreme rainfall?
Posted by: Surly Bond

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 18:20

Like, any advance on a gust of 100 knots from the strange direction of WSW at 11:29 pm at Lucinda?
Posted by: Squeako da Magnifico.

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 18:23

The eye/inner core of TC Yasi unfortunately didn't go over the top of many AWS except of Willis Island where the Anemometer failed. It was travelling too fast to produce extreme rainfall over any particular location. Where 24hr rainfall total records up in North Tropical QLD coast/ranges are above 500mm+
Posted by: Darren J

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 20:05

> Like, any advance on a gust of 100 knots from the strange direction of WSW at 11:29 pm at Lucinda?

I think Lucinda AWS may have sustained significant damage during the night, as:

i) The wind direction was showing S up until 9am this morning when the prevailing winds in surrounding areas were actually from the North. This may have been due to the wind vane being damaged so that it swung 180 deg (Willis Island AWS had a similar problem)

ii) The temperature at 1:10 am and 1:12am was 54.5 and 63.7degC
Posted by: Pacman

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 20:44

Pretty much SB, that's why we have been screaming for Doppler radar up here. Imagine if we had doppler when TC Yasi came through, many would have been able to see where the severe winds where or embedded tornadoes during the onslaught. Oh well i guess it is only a matter of time.
Posted by: Surly Bond

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 20:51

By BS detector is twitching with forecasts of heavy rain in several states "associated with" T C Yasi.
What rain would be forecast in these states if there was no T C Yasi?
Other Tropical Cyclones seem to have had no effect on the weather in my neck of the woods, and there seems to be no effect now.
Posted by: Unsettled

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 21:02

Check the satellite, SB - this is a massive system. We're getting hammered with rain in Cairns ATM, and the centre is probably 600km away.
Posted by: Popeye

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 03/02/2011 22:16

Its funny you know, they put data gathering Buoys all over the earth's oceans yet in this day and age and with technology and equipment so advanced we don't put a grid of land Automated Weather Stations along cyclone prone coastlines. I understand people realistically only want weather information from a town or city but imagine the amazing figures that we would see if this grid was in place. Too much $$$ obviously but nice to imagine happening one day. It also seems they need to build them stronger these days to. Quite a few have chucked a whoopsie right at the crucial moment.
Posted by: The Doo Crew

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 00:25

Can someone with the technical knowledge and qualification explain this to me...
Let me begin this rant with a most sincere apology to those how have just experienced Yasi, and sustained a night of what was probably considerable fear. But if Yasi came across the coast at a Cat 5 - I'll eat my hat! Having survived Tracy, and several smaller cyclones in years after - and my husband having survived George, Rachel and Lawrence in 2009 - we have a wealth of experiences firmly locked in memory - Cat 5's produce LUNAR LANDSCAPES. From published images I can still see trees standing EVERYWHERE - they still have LEAVES. Yes, there where weatherboard cottages demolished, and a few roofs - but this is not the path of destruction a CAT 5 cyclone leaves. Banana plantations and Africian Mahogany trees fall over in monsoonal "knock em' downs"... Come On People!!!! Instruments failing over up and down the coast and UNDER 200Kms - Bunnings weather stations survive at 200km....within a 100kms of the eye of a CAT 5 - recordings of 103.7km????????????? Live Webcam broadcasts showing blustered palms??? Yes I know it passed in low population area -but then so did Lawrence. There was not a stick of debris to hurl on Eighty Mile Beach - but still a LUNAR LANDSCAPE!!! Something is seriously out of whack here...
Posted by: Hinezy

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 07:45

Hi everyone,

I'm so glad that everyone who experienced this cyclone managed to get through relatively unscathed! Andy Barber and myself travelled up as far as Ayr and Alva Beach to chase Yasi and i'll have plenty of HD video to post later on today! Here is some mobile phone video tho' of its approach near Alva Beach just south of Townsville about 10 hours before it made landfall. At this stage the winds were becoming sustained near the 100km/h mark. Sorry about how shaky it is, but as you can imagine it was quite difficult to even stand up let alone hold the camera steady!

Posted by: Surly Bond

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 08:58

Unsettled, I watch the satpics all the time.
It seems to me that the cyclone drags or pushes adjacent weather meso-systems around without necessarily changing them much.
Why do you link Cairns' current heavy rain with T C Yasi?
Posted by: Surly Bond

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 11:57

Townsville, gusting to 75 knots at 01:30:
http://www.weatherzone.com.au/station.js...1&dt=02/02/2011
http://www.weatherzone.com.au/station.js...1&dt=03/02/2011

Ingham,
http://www.weatherzone.com.au/station.js...1&dt=02/02/2011

Well, I got that link up, then it vanished, and reverted to Townsville.
I dunno.
Posted by: Unsettled

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 12:40

Originally Posted By: Surly Bond

Why do you link Cairns' current heavy rain with T C Yasi?

That would be the feeder band for the (ex) TC passing directly over us at the time? Fairly clear evidence I would've thought.
Posted by: clevelandtony

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 13:59

re Doo Crew.I too am confused as to the mixed effects of Yasi and have spoken to numerous people who have experienced Cat 4 and 5 cyclones and don't feel this event matched the ferocity of previous ones.I'm hoping the knowledge people on this site can explain..Was there too much hype leading up to crossing.?.Was it a 5 or high 4 on crossing.?Is the lack or failure of monitoring instrumentation contributing to these questions not being answered? why with such a wide eye was the destruction not more significant?.These questions need to be answered by those with the tech ability to do so particularly for future events.
Posted by: adam17

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 14:43

Posted by: Firepac

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 14:59

Originally Posted By: clevelandtony
re Doo Crew.I too am confused as to the mixed effects of Yasi and have spoken to numerous people who have experienced Cat 4 and 5 cyclones and don't feel this event matched the ferocity of previous ones.I'm hoping the knowledge people on this site can explain..Was there too much hype leading up to crossing.?.Was it a 5 or high 4 on crossing.?Is the lack or failure of monitoring instrumentation contributing to these questions not being answered? why with such a wide eye was the destruction not more significant?.These questions need to be answered by those with the tech ability to do so particularly for future events.


The BOM is the most qualified to answer your questions and without a doubt will, in due course, release a report into TC Yasi which will address those concerns.
Posted by: Surly Bond

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 15:00

Thanks for the graphs, Adam, but is that Ingham or Townsville?
Ingham is the one I failed to access.
Posted by: Surly Bond

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 15:06

Adam, I am almost certain those are Townsville graphs, but you have elected to use a km/hr scale and I elected knots.

Perhaps Ingham has no AWS?
Posted by: KevD

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 15:07

C'mon guys - NO MORE ONE LINERS IN HERE - they will be deleted

Please try to keep life a little easier and follow the guidelines

Cheers

Kev
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 16:01

Originally Posted By: clevelandtony
re Doo Crew.I too am confused as to the mixed effects of Yasi and have spoken to numerous people who have experienced Cat 4 and 5 cyclones and don't feel this event matched the ferocity of previous ones.I'm hoping the knowledge people on this site can explain..Was there too much hype leading up to crossing.?.Was it a 5 or high 4 on crossing.?Is the lack or failure of monitoring instrumentation contributing to these questions not being answered? why with such a wide eye was the destruction not more significant?.These questions need to be answered by those with the tech ability to do so particularly for future events.

I think there are numerous things that contribute to this attitude ....

#1. Yasi did not hit a major urban location like the Tracey's / Katrina's of the media's world. Therefore while the damage is pretty bad in the areas it did hit, the human impact is far less severe ...

#2. Yasi successfully avoided the BoM's AWS's ... the only one it did actually hit, it destroyed. At closest approach, the closest AWS to the eye was Lucinda at about 50-60km from the eyewall ... so people dont see the emotion laden numbers they were secretly hoping for.

#3. Building standards / codes are so much improved and more tightly enforced than they have been in past cases. In Katrina, it hit a very poor city with lots of low lying areas subject to destruction in the failure of the leves ... which did fail, leaving hundreds of thousands in trouble ... in Tracey, the codes were nothing like they are today

#4. Warning. In most cases people's experience of events is hightened by the fact that they were not expecting it (eg tracey and Katrina). In this case ample warning was available and this made people automatically prepare themselves for the worst, only to be relieved when the best happened.

IMHO this was about as big a cyclone as it gets. Had it hit Townsville or Cairns head on, we would not be hearing the kind of commentary you mention above.

Australia was VERY very lucky it hit where it did, and is very lucky that we have good emergency comms / buidling codes that are strictly enforced smile
Posted by: opplevelse

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 16:33

oh and of course
#5. Yasi hit at lowish tide ... in fact couldnt have picked a much better time
Posted by: stormboy70

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 16:50

Posted this in the Yasu chat thread

I have googled quite a few Cat five systems both here and in the US and the complete stripping of vegetation is not universal and dependant on the type of vegetation. The homes that were badly damaged had roof failure in the most. Most of the Cat five system in Austalia have hit unpopulated areas and in the case of WA there is not a lot of vegetation to begin with. The lack of storm surge is the only curious thing I can think of but many large system have not produced huge storm surges. There is no set model for any cyclone. Most of the houses in Darwin were very flimsy and not designed to withstand a Cat 1 let alone a Cat 4. Tracy lashed Darwin for 6 continuous hours and had a very small eye. They did not prepare before hand as most had decided it would not strike as one that was forecast to hit two weeks earlier had turned away. So lots of debris around as projectiles. Consider also that the greatest damage to Darwin was on the coast suburbs and the highset homes if you look carefully at the photos the low set homes faired better as did the brick ones. So I don't see any reason not to beleive this was a Cat 5. I think most people had bought into the hype this was going to be 300kmh winds 300km from the centre when this was nver going to be the case it was still a much larger area than Larry. I for one see those images of Tully, Cardwell and Misson beach and say Cat 4/5 damage and no miracle required as people prepared and stayed in the bathrooms as instructed by authorities. Somehow I get this feeling some people are disappointed that Cairns and Townsville weren't leveled ala Tracy and 1,800 aren't dead ala New Orleans, I hope not.

Just to add to this, I was in New Orleans in June 2006 and there was minimal wind damage it was mostly flooding that caused the problems when the levees broke. Katrina was not Cat 5 when she hit she had been down graded to a Cat 3 (205 kmh) at landfall, she also did not directly hit New orleans she hit further West so the eye did not pass over the city.

Just my two cents worth.
Posted by: HermSherm

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 17:55

Remember Our Cat 5 is not necessarily SS Cat 5

Yasi was at the top of SS band 4
Karina was SS band 3 so was Tracey

Mahina cyclone of 1899 seems to be the only SS scale 5 at landfall all the others were 4 at landfall.

From Wikipedia



Comparisons across basins: The terminology for tropical cyclones differs from one region to another. Below is a summary of the classifications used by Regional Specialized Meteorological Centres worldwide (although measurements are taken differently they are re-normalised to 10 min readings:


10-minute sustained winds categories

knots KPH MPH

64–72 119-135 74-84
73–85 135-159 84-99
86–89 159-167 99-104
90–99 167-185 104-115
100–106 185-198 115-123
107-114 198-213 123-132
115–119 213-222 132-138 Yasi about here
>120 >222 >138 Mahina here

Regions

N Indian Ocean IMD - SW Indian Ocean MF - Australia BOM - SW Pacific FMS
- NW Pacific JMA - NW Pacific JTWC - NE Pacific & N Atlantic NHC, CHC, & CPHC

12 64–72 119-135 74-84
Very Severe Cyclonic Storm (IMD)
Tropical Cyclone (MF)
Severe Tropical Cyclone (3) (BOM)
Severe Tropical Cyclone (3) (FMS)
Typhoon (JMA)
Typhoon (JTWC)
Hurricane (1) (NHC, CHC, & CPHC)

13 73–85 135-159 84-99
Hurricane (2) (NHC, CHC, & CPHC)

14 86–89 159-167 99-104
Severe Tropical Cyclone (4) (BOM)
Severe Tropical Cyclone (4) (FMS)
Major Hurricane (3) (NHC, CHC, & CPHC)

15 90–99 167-185 104-115
Intense Tropical Cyclone (MF)

16 100–106 185-198 115-123
Major Hurricane (4) (NHC, CHC, & CPHC)

17 107-114 198-213 123-132
Severe Tropical Cyclone (5) (BOM)
Severe Tropical Cyclone (5) (FMS)

115–119 213-222 132-138
Very Intense Tropical Cyclone (MF)
Super Typhoon (JTWC)

>120 >222 >138
Super Cyclonic Storm (IMD)
Major Hurricane (5) (NHC, CHC, & CPHC)


There are other scales that are not officially used by any of the Regional Specialized Meteorological Centres or the Tropical Cyclone Warning Centres. However they are used by other organizations, such as the National Oceanic and Atmospheric Administration. An example of such scale is the Integrated Kinetic Energy index, which measures the destructive potential of the storm surge; it works on a scale that ranges from one to six, with six having the highest destructive potential.[21]

Accumulated Cyclone Energy (ACE) is used by the National Oceanic and Atmospheric Administration and other agencies to express the activity of individual tropical cyclones that are above tropical storm strength and entire tropical cyclone seasons.[22] It is calculated by taking the squares of the estimated maximum sustained velocity of every active tropical storm (wind speed 35 knots or higher) at six-hour intervals.[22] The numbers are usually divided by 10,000 to make them more manageable. The unit of ACE is 104 kt2, and for use as an index the unit is assumed.[22] As well as being squared ACE can also be cubed, and this version is known as the Power Dissipation Index (PDI).[23]

The Hurricane Severity Index (HSI) is another scale used and rates the severity of all types of tropical and subtropical cyclones based on both the intensity and the size of their wind fields.[24] The HSI is a 0 to 50 point scale, allotting up to 25 points for a Tropical cyclone's intensity and up to 25 points for wind field size.[24] Points are awarded on a sliding scale, with the majority of points reserved for hurricane force and greater wind fields.[24]
Posted by: S .O.

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 20:57

RE Yasi not being Cat 5 .

Perhaps the coastal mountains that outer category gales of Yasi encountered obviously slowed it down dragged it west and perhaps reduced the number of tornadoes that it could of produced .

The North west of WA is pretty flat and dry (normally) so the cyclones strength would reach maximum just before striking coast as opposed to FNQ cyclones that once the outer winds reach landfall they spin into land with the nw-se angle of coastline compared to ne-sw angle of WA .

If anything i've mentioned is incorrect please feel free to disect it , as i'm trying to apply logic to it rather than years of text book Meteorology Qual's .
Posted by: S .O.

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 04/02/2011 21:17

Agreed , WA has v-little vegetation on NW Coast . And what is there is in SAND , that tends to not help vegetation hold in. So Cat 3 on that coast would have visual damage of a Cat 4 in FNQ . As evidence note the Mission Beach resort where a solid gum tree was snapped at ground level and fell whole ......
Posted by: Dave-Wx

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 05/02/2011 00:12

I'd like to second all of what opplevelse said, and much of what Mr stormboy70 said as well (also nice to see you back on the forums! wink )

In particular I'd like to emphasise the comment about the worst of it not hitting a major urban location...going by the radar loop, the area from around Dunk Island to Cardwell was in the prime spot for the favoured SE to SW quadrant of the eyewall, in particular Tully Heads and what looks like pure bushland from there to about 5-10km N of Cardwell. Its not surprising then that the most severe damage that I've seen so far is in Tully Heads, looks like genuine Cat 5 damage there to me. And I daresay that if you hired a helicopter to fly over 'Edmund Kennedy National Park' some of the most severe tree damage from this event would be seen in this area too.

Here's a map of the area of interest by the way, to compare against where the southern part of the eyewall tracked.

Posted by: HermSherm

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 05/02/2011 02:49

Just of note

Yasi may have some significance as a landfall cyclonic event (continental landfall that is). I've checked measured US systems but not the typhoons of NW pacific. It seems from indicated intensity and size to lay on a pareto front: that is no cyclone/hurricane has had both greater intensity and size at landfall (I'm using the HSI system developed in the US primarily for predictive costs/loss of life based on storm size/intensity only)
Posted by: Jax

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 05/02/2011 21:58

Does anyone know how high the most extreme storm surge occurred on the mainland? I've seen or read estimates between 150-200 metres. I'm not suggesting the surge that did occur wasn't hideously destructive, clearly it was, but considering the talk prior to Yasi making landfall and the references to Cyclone Mahina, I think I'm not the only one who got the impression that even with the lower tide that the surge was expected to be much higher. Can anyone shed any light on that please?
Posted by: S .O.

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 06/02/2011 00:45

[quote=Jax]Does anyone know how high the most extreme storm surge occurred on the mainland? I've seen or read estimates between 150-200 metres. I'm not suggesting the surge that did occur wasn't hideously destructive, clearly it was, but considering the talk prior to Yasi making landfall and the references to Cyclone Mahina, I think I'm not .....

Most measurements are in vertical plane (height) , not length .

And at a guess they only went 2.5 m's above the usual high tide limit .
So we are talking a surge of close to 3 m's .

3 reasons it didn't reach that high would be

1, Hinchinbrook Island would have shielded the worst possible surge point

( Cardwell : Vast low lying surrounds of a Bay inlet facing Ne , and close to a point of larger gaps in outer reef , whilst lying in the wake of the southern flank of the eyewall . )

2, As the cyclone approached the land from the North the general trend in tidal flow would have been Nth to Sth causing and earlier peak in tide further north and as the normal tide subsided created a stronger negative drain from within the reef through aforementioned reef passes and negating some of the strength of the surge . Which enevitably peaked two hours before low tide , and also why the BOM released a warning of a second peak as the low tide started helping the flow once more through the gaps in reef .

3, Large tracts of coast nth of cardwell including Dunk , mission Beach a so forth have quite a steep rise from the shore depths . Perhaps deflecting alot of the surge .

Theories only , that no doubt will be answered with a BOM report in perhaps the near future .
Posted by: point breaks

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 06/02/2011 02:16

Due to the requests for information, I thought I'd compile my posts from the general discussion

From the morning of 2nd Feb 2011 (all times EST)

Seems Willis is going to cop the full brunt too... it looks like the eye will only just pass north...

993.5hPa... 72kph windspeed gusting to 93kph


03.44 02/0211:
Wow... 992.4 hPa, 84kph gusting to 104kph.

EDIT: Willis Island, still no significant rainfall yet.

The eyes is probs just on 250kms away from Willis as well

04.10 2/2/11
Latest from Willis Is.
Bar: 990.0 hPa
Windspeed: 83 kph
Gusts: 104 kph
Rainfall (last half hour): 0 mm

04.41 02/02/11
Willis Island
Eye: approx 175km ENE
Bar: 989.3 hPa
Wind: 91 kph
Gusts: 117 kph
Rain (last half hour): 0.6 mm

05.11 02/0211
Willis Island - 5am
Eye: approx 160km ENE
Bar: 987.6 hPa
Wind: 93 kph (50 kt)
Gusts: 128 kph (69 kt)
Rainfall (half hour):0.2mm

05.41 02/02/11
Willis Island - 5.30am AEST
Eye: approx 140 km ENE
Bar: 985.4hPa
Wind: 94kph (51 kt) S
Gusts: 124 kph (67 kt) S
Rainfall (half hour): 0.2mm
(hour): 0.4 mm

06.11 02/02/11
Willis Island - 6.00am AEST
Eye: approx 115 km ENE
Bar: 983.1hPa
Wind: 102 kph (55 kt) S
Gusts: 137 kph (74 kt) S
Rainfall (half hour): 0.4mm

06.42 02/02/11
Willis Island - 6.30am AEST
Eye: approx 100 km pretty much E
Bar: 979.3 hPa
Wind: 100 kph (54 kt) N
Gusts: 133 kph (72 kt) N
Rainfall (half hour): 1.0 mm
(hour): 1.6 mm

At this point, the sudden N change, possibly the pont where Willis Island was starting to fail

07.11 02/02/11
Willis Island - 7.0am AEST
Eye: approx 80 km EEEENE
Bar: 975.7 hPa
Wind: 107 kph ( 58 kt)
Gusts: 139 kph (75 kt)
Rainfall (half hour): 2.0 mm
(hour): 4.2 mm

07.41 02/02/11
Willis Island - 7.30am AEST
Eye: approx 55-57 km EEEENE
Bar: 969.4 hPa
Wind: 122 kph (66 kt) N
Gusts: 157 kph (85 kt) N
Rainfall (half hour): 3.2 mm
(hour): 7.8 mm

08.12 02/02/11
Willis Island - 8.00am AEST
Centre of Eye: hard to say, probably due to lack of penetration by the radar but pretty much E (with a touch of N)
The western eyewall is basically on top of Willis Is.
Bar: 957.9 hPa
Wind: 135 kph (73 kt) N
Gusts: 179 kph (97 kt) N
Rainfall (half hour):10.0 mm
(hour): 13.2 mm

I believe this is the point the Willis Is. information went down.

Hope it is helpful. smile
Posted by: lightning chaser

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 06/02/2011 12:36

With the prospect of TC Yasi going down as a memorable weather event for QLD, i figured it would be a great opportunity for me to experience my first tropical cyclone. Leaving southern NSW monday evening i managed to make my way to northern QLD via the Bruce Highway, arriving in the Cyclone Warned region by early wednesday morning, about 12-18 hours ahead of the expected crossing. Along the way i had filled the car with supplies such as water, food, fuel, torches etc to ensure i could survive in my car for several days should the need arise.

Weighing up factors including the low lying and flat terrain through which the highway runs, the threat of a large storm surge and the prospects of innundation by floodwaters as well as extended power outages - i decided i needed to find a location that would allow me to ride out the cyclose in a reasonably safe area while still having a chance of escape southwards once it passed. Townsville seemed a good compromise between being close enough to the cyclone for some damaging winds but not being too far into what would surely become a disaster zone. Sure i would have liked to experince the strongest winds but the inconvenience didn't seem worth it. I checked into a motel just west of townsville, at the motel were several families that had evacuated from regions closer to the impact.

Throughout the morning and early afternoon winds gradually increased from about 40km/hr up to gale force however there was little if any rain until about midday when it suddenly became quite heavy. During the afternoon i watched the cricket while keeping an eye on the winds and warning messages on the tv. I certainly was quite excited by what may unfold that evening, however was beggining to get quite frustrated when the winds seemed to be struggling to exceed 80km/hr by about 6-7pm. Luckily it was not long after this when the first gusts began to top 100km/hr, then 120 shortly afterwards. It was about this stage that the power blacked out. Gales continued throughout the night peaking at 140km/hr, however it was difficult to get footage with very limited lighting so i found myself sleeping from about 1am till about 6am. I awoke to find the winds had eased slightly but were still perhaps 80-90km/hr with some rain periods.

The motel i stayed in did not sustain major structural damage however much of the lattice work was broken and the shade cloth covering a pool had ripped off and was flapping around. I chose not to drive around townsville to assess the damage however judging by radio reports it was a similar story throughout the city with massive numbers of trees down but minimal structural damage. Cabin Fever was well and truly setting in by late morning with no TV or Air Conditioning, realising that the winds had eased and rainfall had not been excessively heavy i began to make enquiries as to whether the highway to the south would be passable. No one could give me a definite no so i figured i would try my luck. Unfortunately i only made it about 10km before a fallen powerline held up traffic for 1 hour. Once this was cleared i travelled another 40 km only to find a flooded river that local were saying would not be passable for 2 days at least (i later heard that massive traffic jams developed south of this river).

With radio updates indicating that the road west of townsville to charters towers was still passable i figured this would be my only option other than an extended stay in townsville, which at that time was still without power and at threat of having no water. En route to charters towers the tree damge became steadily less as i headed west, the only real concern was the Burdekin River which i had heard was approching the bridge and rising rapidly. It was indeed an impressive sight with water thundering downstream but was still a couple of feet below road level so i was able to cross. 2-3 hours later water was 1 metre above this bridge so it was lucky i got across when i did.

There was little evidence of cyclonic activity south of charters towers and the rest of the long drive home was fairly uneventful. I opted to drive inland through emerald dalby toowomba and then the new england highway. The highlights of the drive home were seeing 2 large feral pigs splashing around in a creek (where's a rifle when you need it?)and then sighting a dingo about 50 km later - both on the road between charters towers and claremont.

Anyway here is the footage i captured in townsville during the cyclone.

http://www.youtube.com/watch?v=WxitzPi5jx8
Posted by: Angrypedro

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 06/02/2011 17:46

An interesting comment has been thrown around by many people in Cairns, hope someone can help. Everyone is commenting on the fact that the wind was roaring like a jet plane taking off, but the wind seemed to be high up and not at ground level. I personally noticed this and assumed i was in a particularly low area and hence not impacted by the fierce winds we could hear. Many people from various parts of Cairns have said the same thing. As far as wind damage goes from what i've seen, damage in Cairns is far less than Cyclone Larry however the wind sounded heaps louder. Larry was certainly loud but the wind gusts seemed to accompany the noise, this was way different. We heard the wind roaring and waited for the gusts to hit (just like Larry did) and they never came. really looking for a technical reason why this may happen, i know what the various AWS around here say but i can't ignore what i saw/heard along with heaps of other people. (Areas commented on Edmonton, Bayview Hts, Edge Hill, Yorkeys Knob, Mt Sheridan) All comments and suggestions are appreciated. Thanks
Posted by: cheekeymonkey

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 06/02/2011 18:08

I can concur with that observation- I posted my experience of it in the Cardwell northwards Feb 2011 thread. Apart from my own observations of this phenomena, I noticed the next morning that all the boats on the hardstand at the Boat Club were not only intact, but their tarps were still there & in one piece. Some of the tarps weren't altogether that well tied, either! I figured that the wind wasn't at ground level there, either.

I also would be grateful for some explanation of this as it's not something I expected.
Posted by: 99wazza

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 06/02/2011 19:01

Originally Posted By: Angrypedro
An interesting comment has been thrown around by many people in Cairns, hope someone can help. Everyone is commenting on the fact that the wind was roaring like a jet plane taking off, but the wind seemed to be high up and not at ground level. I personally noticed this and assumed i was in a particularly low area and hence not impacted by the fierce winds we could hear. Many people from various parts of Cairns have said the same thing. As far as wind damage goes from what i've seen, damage in Cairns is far less than Cyclone Larry however the wind sounded heaps louder. Larry was certainly loud but the wind gusts seemed to accompany the noise, this was way different. We heard the wind roaring and waited for the gusts to hit (just like Larry did) and they never came. really looking for a technical reason why this may happen, i know what the various AWS around here say but i can't ignore what i saw/heard along with heaps of other people. (Areas commented on Edmonton, Bayview Hts, Edge Hill, Yorkeys Knob, Mt Sheridan) All comments and suggestions are appreciated. Thanks


Is it possible that because the wind was coming from a westerly direction the mountains may have played a part in that? I'm not an expert but it seems logical to me.
Posted by: seaspark

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 06/02/2011 19:17

Add Redlynch to your list as we experienced the same thing after the eye crossed and the wind direction changed. Constant heavy wind noise seemed to be bouncing off the hills at higher altitude but we were only getting either still conditions or really heavy gusts that you could hear coming from a distance.
Every cyclone i've been through in this town since 84 has had a different signature left in it's path and this one will be no different although possibly a little harder to judge some of the effects in the areas hit previously by Larry. I guess this question and more will be answered after all the destruction has been measured/analysed by BOM and a report published.
Posted by: Angrypedro

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 06/02/2011 20:01

99wazza, fair comment about W wind, larry was also a westerly wind in cairns, bom actually warned specifically about the increased winds expected on seaward side of the hills north of the cyclone, it was added to the cyc advice late in the evening before crossing, larry saw increased wind speeds at the base of hills in cairns as the wind accelerated down the hills from the west, bom made mention of this in their official report into larry, i beleive redlynch (at base of the hills in nw cairns) recorded one of the highest wind speeds in cairns during larry, because of the hills accelerating the wind, therefore i have to rule out the w wind being the reason for the apparent high level winds. Really interested to find out at what level the winds were circulating in Yasi, sorry if a silly question but must be some data to explain what has been observed, may help during future extreme events. Thanks in advance.
Posted by: teckert

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 06/02/2011 21:26

Back on topic thanks....
Posted by: cheekeymonkey

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 06/02/2011 21:38

OK- so can anyone give us an opinion on this phenomenon where (particularly in Cairns) it has been extensively noted that the winds above us were significantly higher than on the ground????

Been googling like crazy & can't find an answer.
Posted by: cheekeymonkey

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 06/02/2011 22:41

Well- have just spoken to my Dad in the UK (avid weatherwatcher & has sailed the world- seen lots of cyclones, storms etc.)
My understanding of his take on it is this:
The system was very large and moved very fast. The winds were coming from the West over Cairns from the Tableland area, so the mountains would have an influence. The system also created a negative pressure at ground level owing to its intensity & speed. He likened it to an aircraft landing. If the aircraft comes into land at slow speed, it drops altitude very quickly. However if it lands at high speed it drops altitude more slowly due to the negative pressures under it.

Kind of made sense to me- any other thoughts? (may be completely off kilter here)
Posted by: adam17

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 07/02/2011 01:04

It does make sense, but we experienced SE-NE winds and also had the same thing occur. Living quite close to the Mount Stuart, before the power went out, you could see the trees moving more than at the surface?
Posted by: camshaft

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 07/02/2011 21:46

I agree also in caravonica, I could hear trees snapping like twigs in the mountains and sustained wind at higher altitude yet we only go the ocasional gust at ground level! perhaps somthing to do with being so far north of the storms eye and yes the mountains.

Townsville had sustained winds of 100km/h+

Are these the affects of being N and S of the storm?
Posted by: Rocky Raccoon

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 11:08

Gwenda, 1999 = 900
Inigo, 2003 = 900
George, 2007 = 902
Orson, 1989 = 904
Theodore, 1994 = 910
Vance , 1999 = 910
Fay, 2004 = 910
Glenda, 2006 = 910
Mahina, 1899 < 914
Monica, 2006 = 916
____________________
Yasi, 2011 = 922.

See Yasi does not even make it into the top ten of the most intense cyclones of the Austalian region.
Posted by: grumbleguts

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 11:20

The winds here in feluga were the same at ground and above. more so at ground I think. everything downstairs (a 3-drawer filing cabinet for example)was hitting out floor below us. (1.7 metre clearance downstairs) all night for 5 hours.

Feluga is incredibly explose though, the winds were coming straight down the bruce highway due south then due north. We live in an area with nothing but cane fields as far as te eye can see in both these directions.
Posted by: SBT

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 11:53

I have posted this elsewhere and while not too accurate as it is just a home based system I made teh following observations during Yasi as it passed over me in the Townsville suburb of Rasmussen:
Max wind gust before my weather station died was 119kph
sustained 10 minute avergae wing gusts where 87kph
lowest pressure recorded was 990hPa.

It matters little what armchair experts say about STC Yasi.

The BoM has recorded it as a Cat 5 and for all intents and purposes that is what the government, insurance and disaster mamagement will use when writing their reports. What people tend to not take into account is the effects local topography have on winds. For example across Ross River from me is a curved ridge wich forms part of the Mt Stuart complex and has the effect of funneling the nwinds directly up river and squeezing the lower winds between the mountain and the ridge line. This would increase wind speeds not reduce them.
Posted by: windwanderer

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 11:59

hi rocky raccoon,

i was wondering where you got your yasi pressure from? the rammb site has it at 900 if not a fraction lower. is there somewhere else i can find data?
Posted by: !SCHUMMY!

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 19:54

922hpa was YASI's estimated lowest pressure according to BoM at 11am Feb 2. YASI did weaken a bit prior to landfall and crossed the coast with a central pressure of 929hpa......here is the chart from the BoM.

This is from Clump Point, Mission Beach....

Posted by: windwanderer

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 20:30

cheers schummy.

i found the page here. http://www.bom.gov.au/cyclone/history/yasi.shtml glad the full details are up. i've bee ntrying to find something like that for days now.

is it normal for the rammb data to read high?
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 20:35

Guys hoping to have footage up this week, power permitting. SOme information on Yasis effects here at home in townsville.
Highest recorded gust in Townsville - 135kmhr
Estimated highest gust at home going by damage - 170-180kmhr
This is based on the damage to signs, roofing, trees. All the hills around my place resemble Cyclone larry, with all the trees stripped bare, it looks like a bushfire went through.
ONly got power on last night, so six days without power, in 30C temps all night.
Posted by: Nino :0)

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 20:57

Originally Posted By: cheekeymonkey
OK- so can anyone give us an opinion on this phenomenon where (particularly in Cairns) it has been extensively noted that the winds above us were significantly higher than on the ground????

Been googling like crazy & can't find an answer.


Hey Cheeky Monkey I asked your question elsewhere and the answer I got from a US meteorologist was as follows

Quote:
To ninox, most certainly yes the winds could be significantly stronger 100 m off the ground.. In fact, here in the US the NHC makes a point of advising people in cities when a strom is headed for one that the winds in the upper levels of high rises could be as much as one full category stronger than on on the ground. The hurricane's (and TC's) strongest winds are found some some distance above ground level. This is where the role of convection in the eyewall comes into play for the downdrafts in the convection will surface the stronger winds as gusts. This convection is stronger in storms that are intensifying rather than steady state or weakening. Mesoscale structures within the eyewall such as mesovortices can also surface these stronger winds. Such structures are usually found in intensifying storms as well and can result in localized winds far more intense than those supported by the pressure gradient.


Posted by: MareebaWeather

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 21:08

I'm located 5 km from Mareeba AWS, but at least 80 metres higher in elevation.
Mareeba AWS recorded 81 km/h
I recorded 94 km/h (at 5m) before a sensor failed (could of been between (95-100 km/h)

---------------------------

Cyclone

Live Weather Data & Lightning Tracker from Mareeba
Posted by: cheekeymonkey

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 21:11

Thanks Nino:0)
Sort of aligns with my Dad's explanation somewhat. Think I'm getting more of a picture of what happens now,

Cheers
Posted by: Mick10

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 21:32

Originally Posted By: Trav Dog
Guys hoping to have footage up this week, power permitting. SOme information on Yasis effects here at home in townsville.
Highest recorded gust in Townsville - 135kmhr
Estimated highest gust at home going by damage - 170-180kmhr
This is based on the damage to signs, roofing, trees. All the hills around my place resemble Cyclone larry, with all the trees stripped bare, it looks like a bushfire went through.
ONly got power on last night, so six days without power, in 30C temps all night.


certainly alot higher wind gusts around than 135km/h. street signs twisted, massive gums, casuarina's, mangoes snapped off at the stump. going by the damage, alot more severe than Tessi in april 2000 which had max wind gusts of 129km/h.
bom on radio the other morning said winds were strong cat 2/weak cat 3 strength.
be interesting to read all the reports in the future.
Posted by: windwanderer

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 21:34

it's very hard to guess wind speed by eye. my experience is the majority of people can't really tell the difference between 15 knots and 20 knots. extend that out to 50 knots versus 60 knots and i'd say it would be impossible. that's based on 20+ years of sailing.

there is also a difference in wind speed at height. kitesurfers for example usually receive more wind than windsurfers. also, with highrise design. you do account for higher wind speeds the higher the building.

the other item that comes into play is air density due to temperature. the easy way to explain that without getting myself into trouble is this. 25 knots in winter has more power than 25knots in summer. i noticed that some of the stations recorded cat 1-2 wind speeds but their pressure readings were low. it could be that the wind had more power due to lower temperatures.

for those wondering about the wind being higher up, that is something i have noticed before when sailing. i have no scientific explanation but to say it think that's possible.
over land, it could also be due to shielding. if you live in a built up area the wind would not "touch down" as it lifts to go over obstacles. building codes also take this into account. anything can prevent the wind from touching down, trees, hills, fences, walls, buildings etc.

it is also worth mentioning that the building codes when calculating design wind loads take into account, region, terrain, shielding, slope and location as all of these items will effect wind speed.
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 21:36

Wind wanderer, its all to do with the friction layer which lies from ground level, to about 20 metres above our heads. The winds can increase to up to 50%^more than ground level, just a few metres up.
Posted by: windwanderer

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 21:40

yep, the friction layer varies great depending on fetch and topography. 9m is more than enough for a difference.
Posted by: cheekeymonkey

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 21:46

Yes, I've noticed it whilst sailing, too. We use this a lot while racing & twist the top of the sail to spill the wind when it's gusty. My sister is a kitesurfer & points her kite further down to create speed, but lifts it to get 'air'.(means get airborne & do crazy things like go upside down & stuff!)
Posted by: thomo

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 21:49


This image below shows the effects Yasi had on the SST's with quite a bit of cooling going on.

Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 21:54

Slowly uploading videos and pictures
Here is looking towards the west from my back verandah, the clothesline is gone !!! no idea were it went, and just near the fenceline used to be covered with rainforest, and you couldnt see the sky, now its all gone.



Another shot



Posted by: windwanderer

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 21:58

Originally Posted By: cheekeymonkey
Yes, I've noticed it whilst sailing, too. We use this a lot while racing & twist the top of the sail to spill the wind when it's gusty. My sister is a kitesurfer & points her kite further down to create speed, but lifts it to get 'air'.(means get airborne & do crazy things like go upside down & stuff!)


yeah, it's commonly used in sailing because of wind gradient, upwash and angle of attack. in short it reduces drag.
Posted by: Tuco

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 22:03

Why has the BOM removed the wind speeds and rainfall from the days of the cyclone on the February 2011 Daily Weather Observations?
www.bom.gov.au/climate/dwo/IDCJDW4128.latest.shtml
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 22:06

Originally Posted By: Trav Dog
I am so confused by the BOM.

If it headed WSW from now it would hit between townsville and Cardwell, if it moved WSW in the next 6 hours, it would move towards inhgam - cardwell.


Okay so the latest model runs are
CMC - Ingham too cardwell crossing
EC - Cardwell Crossing
GFS - Ingham to cardwell

What am i missing????? I think they have put it over cairns too alert the city, i dont think cairns will get nailed. The models are showing alot of consistancy, and they are the best we have


Just bringing this post up from the depths.....
So come on guys, can anyone tell me why the BOM put the crossing point so far nroth, when all models but ACCESS had it around cardwell to ingham???
The first track map the bom put out was the most accurate. I cant believe they went against the best models and stuck with ACCESS...This cyclone was always going to hit Very close to cardwell.
Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 08/02/2011 22:09

Originally Posted By: Trav Dog
Originally Posted By: Trav Dog
I am so confused by the BOM.

If it headed WSW from now it would hit between townsville and Cardwell, if it moved WSW in the next 6 hours, it would move towards inhgam - cardwell.


Okay so the latest model runs are
CMC - Ingham too cardwell crossing
EC - Cardwell Crossing
GFS - Ingham to cardwell

What am i missing????? I think they have put it over cairns too alert the city, i dont think cairns will get nailed. The models are showing alot of consistancy, and they are the best we have


Just bringing this post up from the depths.....
So come on guys, can anyone tell me why the BOM put the crossing point so far nroth, when all models but ACCESS had it around cardwell to ingham???
The first track map the bom put out was the most accurate. cant believe they went against the best models and stuck with ACCESS...This cyclone was always going to hit Very close to cardwell.


If you looked at the track, you would see it crossed over Mission Beach which is between Cardwell and innisfail. I would say that BoM was spot on in their forecast as the system approached. The models were generally too far south. Perhaps you need a basic geography lesson!
Posted by: Mick10

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 09:04

this thread is now unlocked, please think about your posts and not let a good thread turn into a personal slanging match.
Posted by: @_Yasified_shak

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 10:30

a compilation track map from the BOM

Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 18:21



I just did my geogrpahy lesson and wow im back andIm asking the question again.
So no one knows why the BOM had it over cairns, when no trustworthy tropical model had it over them, and were going for a more cardwell crossing???
Do people think they did this to try and scare the public around cairns so they remained vigilant???

Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 18:32

Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 18:32

Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 18:49

Originally Posted By: Trav Dog


I just did my geogrpahy lesson and wow im back andIm asking the question again.
So no one knows why the BOM had it over cairns, when no trustworthy tropical model had it over them, and were going for a more cardwell crossing???
Do people think they did this to try and scare the public around cairns so they remained vigilant???


Talk about conspiracy theory! If you look back, JTWC had Yasi tracking right over Cairns with sustained 130kt winds in one of their forecasts. If you look at the life of the system after it was taken over by BoM, most of the forecast tracks had Yasi crossing between Gordonvale and Rollingstone, with only two I recall being over the Cairns area. As the centre got closer, the BoM tracks seem to cluster in the Mission Beach area (which proved correct). The dynamic models are only there for general guidance and as system gets closer, forecaster knowledge and experience takes over not to forget radar imagery and met obs.

If you think there is a problem with BoM's cyclone forecasting (as you obviously do), then I suggest you undertake a 3 year science degree in either maths and physics at JCU and then a one year graduate diploma in meteorology at the BoM HQ in Melbourne. Then after about 5 years work experience your criticisms of BoM may then be taken on board by the highly trained people in the organisation.
Posted by: Popeye

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 18:54

Trav, I suppose they had to weigh it up. Trust the models or take it into account the real risk that Yasi could hit a big city head on. What would you have done?

It had been travelling nearly west with a bit of WSW for several thousand KMs so it was never out of the question that Cairns wasn't to be crossed. Even up to 6 hours from crossing, Yasi was steaming in with a slightly more westerly component than WSW and Cairns was potentially still in very close proximity to the firing line. If it wasn't for that pronounced almost SW shift in the 4-5 hrs prior to landfall the outcome today could have been a lot different. Especially when the BIG CAT 5's can sometimes defy the expected and do the unexpected especially with Yasi being such big solid cyclone who had some reasonable momentum behind her. BOM did the right thing considering where it eventually crossed isn't really that far from Cairns.
Posted by: Pucci.

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 18:57

Originally Posted By: Trav Dog


I just did my geogrpahy lesson and wow im back andIm asking the question again.
So no one knows why the BOM had it over cairns, when no trustworthy tropical model had it over them, and were going for a more cardwell crossing???
Do people think they did this to try and scare the public around cairns so they remained vigilant???



I'm merely a single cell amoeba in the developmental world of meteorology, but I'd be very surprised if BOM did something like that. Credibility would have to be their number one priority and I'd imagine their acceptable margin of error (in relation to that credibility), is already very tight.
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 19:05

Stevo your missin the point, this is the first time i have ever seen the BOM go with a access model instead of EC, EC had for many runs it hitting near cardwell, and the BOM didnt recognise this at all.

Your missing the point completly. NO MODEL that is trustworthy with tropical systems had it around cairns. I talked to independent met about this 2 days prior to landfall, and he said he has no clue.

So really, take a look at the facts on the table. The BOM had no reason to put it straight over cairns.
Posted by: adam17

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 19:15

Isn't that line a general line, with error factors north and south of that line? Given the information at the time, and the speed it was traveling at, I didn't expect it to curve as much as it did in the end, Cairns did look like it was in the firing line.

Contrary to your thoughts there Trav.. its pretty obvious BoM was being over cautious, and I think they would have had quite a few reasons to put it over Cairns. Luckily for them it didn't eventuate. Just because you've chased a few storms, took a few readings and appeared on TV a few times, doesn't make you a meteorologist.
Posted by: Pucci.

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 19:22

Hmmm. I could be wrong, but I didn't think Trav Dog was disagreeing with BOMs 'findings' but was wondering more about their 'process'

*slinks back into the corner of the room and resumes minding her own business*


Posted by: adam17

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 19:25

I don't think so either, but to accuse the agency of relying on this model or that model, it just isn't the case, there are alot more factors taken into forecasting than just one model. You cannot criticize the "process" unless you understand what the "process" is.
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 19:30

I know people who know the process, and they had no clue at all as to why they were following ACCESS instead of EC, GFS and CMC, who were all very similar.
Posted by: nitso

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 19:36

I have just submitted my data to the BoM now for this cyclone and our little toy cyclone Anthony. I will upload the data to our website and to our chase thread shortly.

I have had 2 major television stations contact me about why the BoM got it wrong - that's the stations not the individual broadcasters like WIN NEWS, TT, ABC Radio etc and all i had to say was that I was dumbfounded by the map that had it crossing north of Cairns. While I reminded them that subsequent maps were obviously corrected, and that overall the BoM performed quite well with this system, for that 12 hour period they went off the ball BIG TIME

The more knowledgeable weather presenters were very aware of this slip up. An ensemble of models had predicted coastal impact for days between the Innisfail to Ingham region yet one of those models UKMET had the upper ridge building to the west and continuing to track the system west and even WNW. Now even to my untrained eye that was nothing short of ridiculous with a short wave trough over inland Australia obviously not picked up by UKMET at the time. So I'm assuming that the BoM being much better trained than myself also discounted that model as being highly improbable if not impossible.

That left good old ACCESS, ACCESS has been and continues to be the worst performer in all weather related forecasting. Why would you go with the only model that predicted a north of Cairns crossing when all you available accurate model guidance suggested an impact zone 100 - 250kms south of where ACCESS was estimating??? My only thought is that the BoM took the forward speed of motion and momentum of the system due to its sheer size into their calculations believing that the system would take much longer to respond to a change in the atmospheric steering flow. That is seriously the ONLY thing I could think of as to why the mets on duty that night would have made such a massive error.

I think to their credit, once they realised the extent of their error from the night before, their maps quickly reflected this awareness by about mid morning of the day it hit. However they were still playing it safe with the Cairns area until mid afternoon, when it was obviously going to strike south of Innisfail.

We had told a number of news networks in the morning to disregard the BoM's overnight track maps and that they needed to get to the Cardwell and Tully region if they wanted to be at ground zero. Channel 7 were the only ones that listened to us somewhat stationing crews in Ingham and I believe Tully. We've had about 6 phone calls since from the news networks wondering the very thing that Trav was asking (why did they get it so wrong 24hrs out from landfall), what you got in this post was the version I have given them.

I guess only the BoM know why they erred, but I put this to you. . .

Would you rather they made this error and got proven wrong or would you rather they nailed Cardwell and then the system hits further north? I daresay we would all agree it was better to be cautious.

I have a far more cynical/conspiracy theorists view as to why they got it so wrong for that brief period, but I will not discuss that publicly nor will I share that reason with the mass media. Those of you close to me will know what I'm alluding to.
Posted by: Popeye

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 19:54

I am not sure the exact time that the BOM had it crossing north of Cairns but from memory it was in a period where the WSW curve was supposed to be happening but it wasn't. I remember Thunderstruck (sorry mate)even saying that the westerly path was continueing and it now placed it further north in the potential track than perviously forecast and that he personally thought that on current projectory a crossing Between Cairns and Port douglas was a chance. With BOMS maps out 3 hrly compared to EC, GFS, JTWC being 12 hourly maybe the more real time maps from BOM were more realistic than the 12 hr models. They were adjusting their maps according to the recent movemnt of the system. If we had to wait for 12 hour updates at the time of crossing they would be useless.

I am a bit surprised you guys are actually argueing the point and having a go at the BOM maps. Of all people I would have expected that 36hrs before landfall you guys would have been considering all models and their crossing points but at the same time respecting the fact that nothing was set in concrete with a crossing point that far out and that things could change.
Posted by: nitso

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 20:24

We love the BoM's maps, they are fantastic and for a very long period of time we were really using them to formulate a good chase location. However for a 12hr period overnight the night before crossing we threw them out and superimposed models over each other and came to the conclusion that Cardwell was the prime target.

Hey bear in mind we were wrong too, Cardwell got the edge of the eye but not the eye itself. So I'm not saying that we were right and the BoM wasn't - far from it. All I'm saying is that there was a 12hr period where the BoM had it wrong and I think to their credit the mistake was rectified reasonably quickly and all subsequent track maps were spot on. Once we felt that they were back on target we started using them again. You're spot on having guidance every three hours from the BoM and every hour from JTWC makes our task sooo much easier. And we are very grateful for the assistance those maps and JTWC's satellite guidance provide, but for a 12hr time period I had to second guess every decision I was making because it wasn't taking me to the same spot as those maps and I had media second guessing me and even some of my chase mates were going ummm Nitso are you sure Cardwell is the place to be?
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 20:38

All i remember is us huddled around the CIMS site, waiting for the South WEST movement, and it was a scary but exciting prospect seeing it happen in front of our eyes with date of longitude and latitude.
Posted by: cheekeymonkey

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 20:46

The shifting of the BOM's overnight track on the Tuesday night was the main focus of our attention, as it helped us make the decision to stay & bunker down rather than to evacuate (we are 5m above sea level & near the beach at Yorkeys).
We were ready & packed to go, however I still have no issue whatsoever with the BOM tracks. If Yasi had wobbled just a few degrees over that night, I am sure we could possibly have been in the firing line & would've evacuated on the Wednesday morning.

It is unwise to be complacent, regardless of models & you can only make decisions on the information you have at hand.
Posted by: Popeye

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 20:52

I remember hearing Nitso's voice on the live feed when he was seeing the SW movement. It almost seemed like relief (if that is a way to describe it) to see it doing what a lot of models had forecast it to do and you guys were obviously waiting to happen. There must of been a point where you guys thought ahh its going to keep heading in on its trajectory between Cairns and Innisfail.

Was the eroding ridge always sitting out from the coast or did it occur in the few hours before crossing. I remember reading JTWC updates leading up to the crossing saying a SW turn after landfall but they were not certain on this at the time like it could of happened just prior to crossing. Cairns might have been saved a lot more damage by a few hours in time.
Posted by: Mick10

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 21:01

from my experience, i remember the BOM on the Tuesday night having the system crossing over or near north of cairns. at that stage the eye was expected to cross about 150-200km north of willis island.
first thing the next morning as the eye was becoming visable on the willis radar i noticed the cyclone was much further south of where the BOM had predicted it to be 10hours earlier. yet they still maintained a crossing near cairns.
all of wednesday morning, i was fielding question after question at work from journo's up and down the coast about will cairns get hit? i maintained a cardwell to innisfail crossing the entire time based on the model consensus, the location of the eye as she moved over willis and of course the information from members on this forum.

what we are lucky is that this girl hit between two major cities, alot of the general public do not understand how close a call this was for both cairns and townsville. 100km further south of north and either city would have been in serious problems.

today i was erasing some footage we took last week prior to anthony crossing. for one of our stories i used the GFS model from the friday before impact. gfs had the system crossing right where it did end up making landfall. not bad at all imo.
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 21:06

Originally Posted By: Popeye
I remember hearing Nitso's voice on the live feed when he was seeing the SW movement. It almost seemed like relief (if that is a way to describe it) to see it doing what a lot of models had forecast it to do and you guys were obviously waiting to happen. There must of been a point where you guys thought ahh its going to keep heading in on its trajectory between Cairns and Innisfail.

Was the eroding ridge always sitting out from the coast or did it occur in the few hours before crossing. I remember reading JTWC updates leading up to the crossing saying a SW turn after landfall but they were not certain on this at the time like it could of happened just prior to crossing. Cairns might have been saved a lot more damage by a few hours in time.


Definatly was reflief for two reasons -
1. Cairns wasnt going to be completly destroyed.
2. We chose a place to stay ( inhgam ) and left cardwell knowing it should end up pretty close to there. So we made the call to head south to get out of the danger zone, and if it didnt do the SW turn as models predicted, we would have missed out on the best chasing opportunity ever.

I must say its amazing watching everything unfold.
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 21:08

The ridge was actually stronger and more persistant that forcast i think popeye, throughout the BOMs track maps, they had it turning WSW but it took alot longer than expected, and i guess this is why the BOM panicked maybe for a few hours.

I think that Land intereaction, and possibly further breakdown in the ridge aided in the south west movement. Its common for cyclones to dip South west before landfall on the Queensland coast i believe. I was personally thinking it was more land intereaction than anything, and this happenede a bit earlier than usual due to the massive size of yasi.
Posted by: Unsettled

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 21:10

Originally Posted By: Popeye

Cairns might have been saved a lot more damage by a few hours in time.


Too right. I don't see the final crossing point as a vindication of the models Trav & Nitso are championing, rather a indictment of the fact that these systems can only be tracked over an average, or path of best fit. The BoM, in my view, was totally justified at all times in it's forecast track, due to their adherence to the apparent path. The westward swing which had my sphincter clenching was as much a deviation around the mean as the SW jink which, let's face it, saved Cairns a lot of heartache.
Posted by: Popeye

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 21:15

There was a moment there Trav when I thought you guys were going to see a direct hit from the southern eyewall in Ingham. The bend it took was pretty sudden and put your choice of location in the firing line. A slight reduction in angle and you guys probably got a pretty full on experience without the threat of being smashed to pieces. Probably a good choice not to wear undies that night mate. There would ahve been an interesting track map when you changed your pants the next morning if Ingham took a direct hit. lol
Posted by: Unsettled

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 21:17

Originally Posted By: Trav Dog
I think that Land intereaction, and possibly further breakdown in the ridge aided in the south west movement. Its common for cyclones to dip South west before landfall on the Queensland coast i believe. I was personally thinking it was more land intereaction than anything, and this happenede a bit earlier than usual due to the massive size of yasi.

I've heard this before, and I've witnessed it apparently being borne out time and time again, but I've never read anything technical on it. Is this even something that can be empirically supported/disproven?
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 21:18

We already had the plan to head back to townsville, if it was going to hit closer to ingham rather than cardwell mate. Storm surge footage would have been epic. Im putting some storm surge videos up now on youtube actually and should be on much later tonight of the strand.

If it didnt move west for 3 hours popeye, we were in trouble though smile
Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 21:42

Originally Posted By: Unsettled
Originally Posted By: Trav Dog
I think that Land intereaction, and possibly further breakdown in the ridge aided in the south west movement. Its common for cyclones to dip South west before landfall on the Queensland coast i believe. I was personally thinking it was more land intereaction than anything, and this happenede a bit earlier than usual due to the massive size of yasi.

I've heard this before, and I've witnessed it apparently being borne out time and time again, but I've never read anything technical on it. Is this even something that can be empirically supported/disproven?


I am not convinced of this if you look at the tracks of Winifred, Rona and Larry (all shifted towards the west as they neared the coast). Every cyclone is different so hard to generalise. In fact, Winifed was tracking SSW towards Townsville (on high alert) but suddenly changed sharply to the west and crossed over north Mission Beach.

A slight change in steering dynamics could have forced Yasi more towards the west to cross just south of Cairns, but luckily for Cairns the track went more SW (unlucky for people south of Innisfail).
Posted by: Locke

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 22:31

Originally Posted By: Trav Dog
The ridge was actually stronger and more persistant that forcast i think popeye, throughout the BOMs track maps, they had it turning WSW but it took alot longer than expected, and i guess this is why the BOM panicked maybe for a few hours.

I think that Land intereaction, and possibly further breakdown in the ridge aided in the south west movement. Its common for cyclones to dip South west before landfall on the Queensland coast i believe. I was personally thinking it was more land intereaction than anything, and this happenede a bit earlier than usual due to the massive size of yasi.



Trav I have chased 6 storms in QLD and the NT and each one has had their track turn Northwards to some degree as they approached the coast. I guess my experiences have been different from yours.
Posted by: S .O.

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 23:16

Originally Posted By: Locke
Originally Posted By: Trav Dog
The ridge was actually stronger and more persistant that forcast i think popeye, throughout the BOMs track maps, they had it turning WSW but it took alot longer than expected, and i guess this is why the BOM panicked maybe for a few hours.

I think that Land intereaction, and possibly further breakdown in the ridge aided in the south west movement. Its common for cyclones to dip South west before landfall on the Queensland coast i believe. I was personally thinking it was more land intereaction than anything, and this happenede a bit earlier than usual due to the massive size of yasi.



Trav I have chased 6 storms in QLD and the NT and each one has had their track turn Northwards to some degree as they approached the coast. I guess my experiences have been different from yours.


Has everyone thought too much about land interaction , or other steering atmospheric influences . Maybe SST's and surface drag/cooler water replacement had an effect either it be in a steering influence/fuel attraction or it causes the overly large system to weaken as it ran out of (new) undisturbed warmer water . What steering influence/inertia would be the resultant of the reasonably sharp drop in intensity ???
Posted by: ol mate

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 23:22

Originally Posted By: Popeye
There was a moment there Trav when I thought you guys were going to see a direct hit from the southern eyewall in Ingham. The bend it took was pretty sudden and put your choice of location in the firing line. A slight reduction in angle and you guys probably got a pretty full on experience without the threat of being smashed to pieces. Probably a good choice not to wear undies that night mate. There would ahve been an interesting track map when you changed your pants the next morning if Ingham took a direct hit. lol


I remember seeing that too Popeye. I nearly crapped in my pants when I saw that all of a sudden Southerly turn on the MTSAT and the Tvl 512km radar. Our fibro house was shaking violently enough, and the thought of Yasi directly hitting Ingham had me trembling in fear!
People in the Abergowrie area, 50km west of Ingham, reported a dead calm of about 10 mins before winds picked up in a different direction. People who had parked cane haulout tractors around their low set homes for extra protection actually had them slide about 15cm. These machines wheigh over 20tonne. There were 3 of them, and they all moved. The Abergowrie College reported a wind gust of 306kph before the station failed.
Posted by: ColdFront

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 23:26

Originally Posted By: Locke
I have chased 6 storms in QLD and the NT and each one has had their track turn Northwards to some degree as they approached the coast.


Larry did.
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 23:35

Yes im wrong for saying that alot turn south west.
I realise larry was riding a very strong ridge, so no chance of SW, only WNW.
However, im not saying it happens every time, but the last 3 cyclones this past year i have chased they have all done this.
ULUI - 200 kilometres from the coast, moved WNW after heading WSW, and then suddenly turned SW towards prossie.
Anthony - Heading WSW, then moved more westerly or even slightly WNW before heading dirctly SW over bowen.
YASI - SW turn 100ks from the coast.

Can only back this theory up during the next few storms. Again, not saying they always duck SW, or NW, but it happens more often than not.


However to myself, most common erratic movement near the coast is WNW - NW and then a sudden shift to the south west.

Wonder if its to do with the infeed and outflow bands moving across the land, would love to see a study on this.
Posted by: Popeye

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 23:44

I know this has been posted in here before but a repost is relevant considering all the great debriefing that has gone on about this system this evening. Speed it up to 22/25.
512kms CAIRNS RADAR LOOP

Absolutely fricken insane!!!!! She was a beast! A monster!!!!
Posted by: S .O.

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 09/02/2011 23:50

[quote=Trav Dog]Yes im wrong for saying that alot turn south west.
I realise larry was riding a very strong ridge, so no chance of SW, only WNW.
However, im not saying it happens every time, but the last 3 cyclones this past year i have chased they have all done this.
ULUI - 200 kilometres from the coast, moved WNW after heading WSW, and then suddenly turned SW towards prossie.
Anthony - Heading WSW, then moved more westerly or even slightly WNW before heading dirctly SW over bowen.
YASI - SW turn 100ks from the coast.

Can only back this theory up during the next few storms. Again, not saying they always duck SW, or NW, but it happens more often than not.


Agree ,

And just to confuse everyone , this is exactly what a hand held circular saw does when it is lowered by its cord (without the guard ) onto a solid wooden floor . ( don't ask how i know ) ... Just think of that analogy , looking at the saw side on spinning clockwise ( just like a sat view of cyclone ) as the teeth on the blade make contact the saw shifts left momantarily and then rolls right . Or for the rev heads , try chocking the back wheels of your car , ( RWD only ) get someone to start it and move thru the gears till rear wheels at great rate of knots . Then with a long pole , push over the chock or trolley stand ..........

Pls . note these instructions in no way make me liable for any sort of Damage .....
Posted by: Thunderstruck

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 09:43

The BoM handled this one very well, I'm not sure what all the fuss is about one of the initial track maps stating Cairns was a chance because it was, there were MANY learned people out there stating this trust me. Two of the EC runs put it VERY CLOSE to Cairns not just ACCESS (which I didn't even know because I have never really looked at it). Yasi was consistently tracking N of the first track progs before coming into line after 2 days. JTWC also reflected this change in model guidance and there was a concern given the forward speed that any deflections would be minimal and in the end they were. They SW turn was very gradual over a few days with the final crossing pretty much where it was expected in the end so a very good forecast and tracking in the end, with very minor corrections to the track map. Yasi was erratic near the coast, he tracked almost due west, then quickly SW and right near the coast tracked almost due west as he crossed before a general WSW trend occured. Not all TC's will produce a severe SW hook like Ului or Anthony did, that is usually but not always reserved to the small TC's which Ului and Anthony were, they were tiny.

TS cool
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 10:07

Slowly getting footage from the last 2 weeks up...slowly

Cyclone Anthony







Cyclone YASI




More to come smile
Posted by: drivenunder

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 10:36

Awesome vids Trav Dog. The sound of that roof banging, or something banging shows the ferocity of that cyclone... and you can only imagine after hours of warping and bending and pulling - its no wonder so many rooftops and buildings blew apart. Awesome stuff!
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 10:59

Cheers mate smile
Just talkin to a guy down the road from me, he recorded 180kmhr gust smile He has a wicked set up.
Posted by: @_Yasified_shak

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 11:12

This is a video from about 4:10pm as the winds were starting to strengthen (and before most of the trees went)
Posted by: @_Yasified_shak

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 11:54

This one is taken at about 11pm while sitting in the bus with the winds coming from the South, you can see the camera move on quite a few occasions when some big gusts came thru (i had it sitting firmly on the steering wheel).The video does not do justice to the wind strength at the time either.
You will have to forgive the audio ath the start for some reason it has been compressed and the kids in the back groud sound like a pack of Chipmunks, but it is good for a laugh!
Posted by: @_Yasified_shak

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 12:12


before and after yasi

Originally Posted By: mission_shak


Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 21:13



The last videos of the old cardwell !!!!!!!!!!!!


Sad to watch frown
Posted by: Popeye

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 22:08

Man that is pretty eerie watching that Cardwell footage. It goes to show the positives in good stormchasers being able to predict 'real' damage and outcomes of systems. All I can say is keep it up. Its only going to benefit peoples safety in years to come as you guys become more well known especially if you guys keep predicting systems they way you do.

There needs to be an alternate for people to turn to and you guys are definately going to get a name for yourselves. Once you iron out the approach to media and dictate them on your terms and a few smaller issues (like a cyclone crossing in daylight would be good) you guys should be able to turn a hobby into a career. Good one!!! Chase across Australia in the wet, Tornadoes in the states in May/June and chillout in the dry season. What a life!!
Posted by: Dawgggg

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 22:33

Cheers bud.
It was sad to know that people had no idea in the world what was going to be left of there homes and shops the next day. In the video you can see the sandbags at the bottom of the doors....if they had known how much power is in these storms, they could have done more to prevent the water inundation, but at the same time, there really is nothing you can do.
All i know is, is that we have on the internet, the last time you will ever see cardwell at its old best, with the lovely green forshore, jetty and play grounds. Now its all sand...just nothing left of that foreshore.

I dont know how the media are going to act when the next cyclone comes. Obviously we already had alot of media attention, and after this one, its going to be big. I think it is time we sat down at a table and sorted out what do we do. We arnt in it for the money, but money helps data really. The more money we get out of this, the more we can put into our research, and that in turn can save lives. By showing people the real forces of nature online, people can have a bettwer understanding of what actually happens in a cyclone, how houses and trees are affected. What they can do to minimise damage around the home. A career in weather forcasting and storm chasing would be awesome, but i just cant see it happening in australia unfortunatly. The only ways i can see it are -
1. The media paying big money for best shots and first exclusive shots of cyclone damage and a cyclone impacting a area.
2. Or actually being approached by a media organistion, and setting up some type of segment, were they send us into a zone and get us to take the best footage, and not only of cyclones, storm events, flood events all around australia. This would be cool, but i think we have to lift our game alot in regards to preparation, video footage etc. before we could get approached at all.

We do know that after we forcasted yasi to hit around the cassowary coast, we had media calling us, wanting to know how we forcasted it, why was it different to the bom ( news channals sent media to cairns and innisfail expecting the doomsday effect ) and we sat tight in ingham knowing we would be the only ones in ingham getting the footage.

Who knows what the future brings.
Posted by: avinet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 22:53

Originally Posted By: ol mate
The Abergowrie College reported a wind gust of 306kph before the station failed.


Is this the highest gust reported so far for Yasi? And what time was it recorded in relation to the passage of the cyclone? From what I can see the eye of Yasi passed a some way to the north of Abergowrie - would this have been a topographic enhancement of the wind along the valley where Abergowrie is situated? If it is accurate it is a very impressive reading so far away from the eye of the cyclone - ?30-40km at a guess.
Posted by: ol mate

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 10/02/2011 23:36

That information was given to my by a staff member from the college who was bunkering down with the students in their dorms on the night. I didnt ask what time sorry. People in the area (further west of Abergowrie) reported being in the eye, the dead silence for 5-10 minures before the winds returned with more force from a different (but not opposite) direction. All the people who have spoken about this have made it clear the wind came from a DIFFERENT direction, not the opposite. By looking at it, it seems they would have passed thru the SE part of the eyewall, from what I understand, is the strongest part of a cyclone. If you go into Google Maps for more of an idea, homes along Caprs's Road and further west seemed to have the most damage, completely wiped off their stupms. I drove up there on Tuesday afternoon. Nearly all of these homes had people living in them, or were simply vacant at the time. I also took note that trees on the western side of the Cardwell Range were severly stripped, and it looked as if a bushfire had gone thru the area. Damage in this area was alot worse than that of Ingham and in fact the coastal areas of Lucinda/Taylors Beach/Allingham. Creekbeds and waterfalls not previouly visable to the naked eye are now in full light for the everyone to see.
Posted by: Green n Lumpy

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 11/02/2011 06:58

Trav, if you are interested for your data on Yasi, just about all our trees fell to the N or NNE which would indicate they all came down about the same time. We are 1km inland from the North of town.
Are you able to pinpoint from your data at about what time this would have happened?
Posted by: Raindammit

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 11/02/2011 08:38

At Bilyana, almost all trees fell towards the NNW or NW, indicating that the SW eyewall was the most destructive there. A few trees fell toward the SSW to SW after the the eye passed through, but not many. The destruction had been done by that point.
Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 11/02/2011 08:42

Originally Posted By: avinet
Originally Posted By: ol mate
The Abergowrie College reported a wind gust of 306kph before the station failed.


Is this the highest gust reported so far for Yasi? And what time was it recorded in relation to the passage of the cyclone? From what I can see the eye of Yasi passed a some way to the north of Abergowrie - would this have been a topographic enhancement of the wind along the valley where Abergowrie is situated? If it is accurate it is a very impressive reading so far away from the eye of the cyclone - ?30-40km at a guess.


This is certainly possible as extreme gusts may have been enhanced by leeward acceleration off the Kirrima Range (gravity waves). How high was the anemometer above the ground? I hope BoM check the site, equipment and data and let us know what they think. This may be an unofficial Australian windspeed record. Very interesting!
Posted by: grumbleguts

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 11/02/2011 08:48

Originally Posted By: Raindammit
At Bilyana, almost all trees fell towards the NNW or NW, indicating that the SW eyewall was the most destructive there. A few trees fell toward the SSW to SW after the the eye passed through, but not many. The destruction had been done by that point.


I don't believe you can use tree felling as an indication of relative wind speed/strength. Trees that fell before the eye, may well have fallen after the eye but had lreay gone. If even one tree was felled to the south it may well show those winds were stronger because it withstood the southerlies and couldn't withstand the northerlies. Also individual tree geography (branch orientation, root orientation etc)
Posted by: Raindammit

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 11/02/2011 09:19

Originally Posted By: grumbleguts

I don't believe you can use tree felling as an indication of relative wind speed/strength. Trees that fell before the eye, may well have fallen after the eye but had lreay gone. If even one tree was felled to the south it may well show those winds were stronger because it withstood the southerlies and couldn't withstand the northerlies. Also individual tree geography (branch orientation, root orientation etc)


True, but I was simply pointing out that almost all the trees fell before the other half of the eye went through. I'm sure if the cyclone approached from a different direction, it would have been a different story. Here's some examples of the force of Yasi at Bilyana:

This mango tree was at least 2m in circumference. The roots are intact but the tree was snapped off at the base (fallen toward the NNW):



Another tree snapped off near the base, about 1.5m in diameter (fallen toward the N/NNW):



Neighbours shed, only a few meters away from our own which was mostly intact. My partner's car was in this shed, and was crushed:



Trees on the Western side of the property, all fallen to the NNW:



Trees against the house, again fallen to the NNW/N:


Posted by: @_Yasified_shak

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 11/02/2011 09:38

Originally Posted By: Rocky Raccoon
Gwenda, 1999 = 900
Inigo, 2003 = 900
George, 2007 = 902
Orson, 1989 = 904
Theodore, 1994 = 910
Vance , 1999 = 910
Fay, 2004 = 910
Glenda, 2006 = 910
Mahina, 1899 < 914
Monica, 2006 = 916
____________________
Yasi, 2011 = 922.

See Yasi does not even make it into the top ten of the most intense cyclones of the Austalian region.



(upon landfall), the first 2 may have been quite intense while out to sea but rapidly weaken near landfall.
Based on the BOM statistics Gwenda weakened rapidly and was only a category 2 upon land fall, indigo also weakened rapidly as it approached the coast and only crossed as a category 1 system
Therefore George would have to be the strongest system Crossing as a Category 5 with central pressure of around 902.
Theodore, 1994 = 910 did not make landfall anywhere near Australia
Glenda, 2006 = 910 Crossed as a Marginal Cat 3 system
Posted by: @_Yasified_shak

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 11/02/2011 11:38

This is a picture of a house the we thought of buying in Tully at one stage!

I have uploaded another 60 odd photo's this time of around Tully In a few of them you can see metal street lights bent up and over pieces of roofing iron wrapped around powerlines.
http://img691.imageshack.us/i/1001660om.jpg/
Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 11/02/2011 18:10

From the JCU website:

Modern buildings take on Yasi

February 11, 2011: - James Cook University’s Cyclone Testing Station (CTS) team is now well advanced on their investigation in the areas most affected by Tropical Cyclone Yasi, focusing mainly on the Cassowary Coast.

The team’s observations show that most contemporary housing has not sustained much structural wind damage, demonstrating that where the building Codes and Standards have been rigidly followed housing has performed well.

Unfortunately some older houses and some houses exposed to storm surge suffered extensive damage.

The CTS team leader in the field, Dr Geoff Boughton, said that the analysis of damage to simple structures throughout the region indicated that the wind speeds on the ground in Tropical Cyclone Yasi were less than those expected in a Category 5 event.

Using techniques developed and refined in previous cyclones, the CTS team has formed a preliminary view that the maximum wind speed in Cyclone Yasi was about the same as that in Tropical Cyclone Larry.

“We estimate that the gust wind speeds in some of the most affected areas were about 220 km/h” Dr Boughton said.

“As the wind speed does not appear to have been greater than the design wind speed of buildings in the region, we would expect that any modern houses should have performed well under Yasi’s wind loads.

“Our observations show that throughout the region, most contemporary housing has not sustained much structural wind damage. It has demonstrated that where builders have diligently applied the Codes and Standards, housing has performed well.”

One item of concern is the general poor performance of roller doors.

“During Cyclone Larry many roller doors in both houses and sheds failed at loads less than the design load and we have observed the same after Yasi.” Dr Boughton said.

The Cyclone Testing Station has previously published an Information Bulletin expressing concerns about roller door performance, which is available on the CTS web site at www.jcu.edu.au/cts.

Other issues identified in the Cyclone Yasi investigation include damage to tiled roofs, guttering and flashings, and the CTS report will include recommendations on these.

“These issues need to be addressed, but overall we have been pleased with the performance of contemporary buildings in the high winds associated with Yasi,” Dr Boughton said.

“The CTS team is grateful for the assistance and cooperation of the people of the Cassowary Coast during the study,” he said.

For further information:

Geoff Boughton, 0419 213603 TC Yasi Team Leader, Cyclone Testing Station or

John Ginger, Research Director, Cyclone Testing Station , 07 47814490.

Cyclone Testing Station web site http://www.jcu.edu.au/cts

JCU Media: Jim O’Brien 07 4781 4822 or 0418 892449

Issued: February11, 2011
Posted by: Tuco

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 13/02/2011 10:39

As this is the technical discussion, when do we get the results of the BOMs analysis of the data?

Their obs page for February is missing the wind and rain data for the 2nd and 3rd of Feb.

I'd love to know what the highest wind gust was. I seriously doubt it was 135kph as stated on the obs page (before it was blanked out) because around 1:30am we were lying in bed and felt the house move several times. (and no we're weren't being 'intimate')
Posted by: FNQ

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 13/02/2011 12:23

Ian Townsend on ABC Radio just compared various Tropical Cyclones

Typhoon Tip 870hPa (Landfall southern Japan)- October 1979-largest (Diameter:2220kms) and most intense TC on record

Hurricane Mahina (1899) was officially 914hPa (27 inches) but it has been suggested it got down to 8880hPA (26inches)- storm surge 13m; Death Toll 285; Recognised as Australia's most intense Tropical Cyclone.

TC Yasi 929hPa

Interesting Links:

http://www.news.com.au/breaking-news/flo...e-1225998762870



TC Larry 940hPa

Source: "The Devil's Eye"- Ian Townsend
http://www.iantownsend.com.au/books/the-devils-eye/
Posted by: FNQ

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 13/02/2011 12:37

Ian Townsend on ABC Radio just compared various Tropical Cyclones

Typhoon Tip 870hPa (Landfall southern Japan)- October 1979-largest (Diameter:2220kms) and most intense TC on record

Hurricane Mahina (1899) was officially 914hPa (27 inches) but it has been suggested it got down to 880hPA (26inches)- storm surge 13m; Death Toll 285; Recognised as Australia's most intense Tropical Cyclone.

TC Yasi 929hPa

Interesting Links:

http://www.news.com.au/breaking-news/flo...e-1225998762870



TC Larry 940hPa

Source: "The Devil's Eye"- Ian Townsend
http://www.iantownsend.com.au/books/the-devils-eye/
Posted by: Tempest

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 13/02/2011 12:39

Originally Posted By: grumbleguts
Originally Posted By: Raindammit
At Bilyana, almost all trees fell towards the NNW or NW, indicating that the SW eyewall was the most destructive there. A few trees fell toward the SSW to SW after the the eye passed through, but not many. The destruction had been done by that point.


I don't believe you can use tree felling as an indication of relative wind speed/strength. Trees that fell before the eye, may well have fallen after the eye but had lreay gone. If even one tree was felled to the south it may well show those winds were stronger because it withstood the southerlies and couldn't withstand the northerlies. Also individual tree geography (branch orientation, root orientation etc)


Ditto,.

Good to see that you house is in fine shape RD. A lot trees down though.
Posted by: Tempest

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 13/02/2011 12:44

I'm assuming the house with the red roof, holy smoke, the other ones destroyed
Posted by: Raindammit

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 13/02/2011 14:12

Yup the red roof is the house. Have been cleaning up here in Bilyana for the last few days, the SES are going to bring in some machinery later to help remove the debris. We have been chainsawing like mad, and it's beginning to look a bit more 'normal' now. smile
Posted by: Qnim

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 23/02/2011 13:16

Hi all,
this is my first post on this great forum.

Regarding earlier posts comparing cyclone intensities, there is a case for cyclone Monica as being the most intense cyclone ever recorded.

"Using the dvorak technique, the peak intensity of the cyclone (Monica) was estimated over 320 km/h (200 mph) along with a minimum pressure below 869 mbar (hPa; 25.66 inHg). At its peak, Monica exceeded a T# of 8.0, the highest ranking on the Dvorak Scale.[12.] However, since the JTWC is not the official warning centre for Australian cyclones, these intensities remain unofficial."

from.......... http://en.wikipedia.org/wiki/Cyclone_Monica

regards,
Peter
Posted by: Qnim

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 23/02/2011 13:23

Sorry I forgot to include link to the hourly (approx) tech data for Monica.

http://cimss.ssec.wisc.edu/tropic/adt/archive2006/23P-list.txt
Posted by: Wet Wet Wet

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 24/02/2011 21:44

Originally Posted By: Qnim
Regarding earlier posts comparing cyclone intensities, there is a case for cyclone Monica as being the most intense cyclone ever recorded.


Yes I’d agree with Monica being rated the most intense cyclone ever observed in the Australian Region. Official estimates by the BoM had peak wind gusts to 360km/h with central pressure down to 916hPa. I disagree with the BoMs 916hPa, and I doubt it got as low as 869hPa. Rather, I believe Monica got down to about 890-895hPa. But anyway, Yasi on the other hand is estimated to have peak winds up to 285km/h. In terms of ranking with past Australian cyclones, despite all the crap the media were raving on about, there’s no way Yasi would even make it into the top 5, probably further down the list rounding out the top 10 or so.

Personally, I even disagree with the BoMs post analysis of Yasi which has it rated as a category 5 cyclone early on February 2nd prior to reaching Willis Island. I remember the 5am update from the BoM when Yasi was upgraded to category 5 stating peak wind gusts were 295km/h. I said to a few other people there was no way Yasi had yet reach category 5, and was still only a mid to high range category 4. In my opinion, Yasi only intensified to category 5 later that day around 1pm once the system was well to the west of Willis Island.
Posted by: @_Yasified_shak

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 25/02/2011 09:29

from the BOM summary page.
At the time of writing there are no verified observations of the maximum wind gusts near the cyclone centre. However a barograph at the Tully Sugar Mill recorded a minimum pressure of 929 hPa as the eye passed over suggesting wind gusts of about 285 km/h were possible. This is supported by measurements (subject to verification) from instrumentation operated by the Queensland Government (Department of Environment and Resource Management) at Clump Point (near Mission Beach) which recorded a minimum pressure of 930hPa. Significant wind damage was reported between Innisfail and Townsville where the destructive core of the cyclone crossed the coast. Tully and Cardwell suffered major damage to structures and vegetation with the eye of the cyclone passing over Dunk Island and Tully around midnight on 2nd February.

From my stand point there is much more damage to tree and foliage in Yasi compred to around Innisfail after Larry.
Posted by: Stevo59

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 25/02/2011 12:00

For those that didn’t catch “Insight” last night on SBS, there is a possibility that Yasi will be officially downgraded to a Cat 4. At the moment BOM has it on its books as a marginal Cat 5 however a wind speed engineer who has done an assessment of the Mission Bch/Tullly area & surrounds, doesn’t believe wind speeds were as strong as predicted and did not exceed 220km/hr. Dr Scott Power from BOM confirmed that this may be true and they are number crunching at the moment before an official record is made.

If you’re interested the show was called “La Nina” and the transcripts are available at:

http://news.sbs.com.au/insight/episode/index/id/346#transcript

In particular the section from about a third-way-through to the end with Dr Scott Power and Dr John Holmes (Wind Engineer, JDH Consulting).
Posted by: retired weather man

Re: Severe Tropical Cyclone Yasi (SPAC, Coral Sea) - Technical Discussion Only - 25/02/2011 12:30

See my comments re above in Yasi General Chat thread.