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#1413157 - 18/03/2017 15:08 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
14th to 24th of March, 2017:
Potential Key features:
  • Deep Southern-Ocean rossby-wave slings NE in the Indian Ocean.
  • Rossby-wave, with significantly-lower 500-hPa temperatures (-30s), reaches the NE edge of the Eastern IO high, intersecting the 576-thickness line.
  • WA surface troughing and low activity drifts SW into the ocean, interacting with approaching rossby-wave.
  • The high in the Bight is disrupted by the intersect (having already been disrupted by isoheight anomalies a week earlier).
  • The disrupted high in the Bight moves further east, allowing more southerly air-streams north near its SW corner.
  • The now-shorter-wave upper trough buckles, allowing the 576-thickness temperatures to wrap around it, disconnecting at the surface from the deep-south trough, potentially dragging East-Coast (Coral-Sea) activity west.
  • This potential [cut-off] system is capable of gaining more latent energy from the tropical north (Broome-GOC-NE QLD-NSW), intensifying pressure and temperature gradient at its core, both vertically and horizontally.
  • Flooding is a potential issue (consequence of this) along the NSW northern Coastal Fringes within this time period, as Coral-Sea moisture ventures south.
  • The troposphere, in this situation, would be fairly unstable with cooler-to-colder air above a milder-to-warm, humid air-mass.
  • A second upper trough ventures NE into the Eastern Indian Ocean, this time buckling (because it is stuck between ridges and the first cut-off).
  • This second upper trough also A. disrupts the 576-thickness NW of Perth WA, and B. drags moisture off a developing surface low near Broome, intensifying its development.
  • The 576-thickness (approaching Adelaide) drags much-higher dew-points (+14 C) in an arc from as far as Broome and SE QLD…again.
  • The first shorter-wave cut-off is likely to add to the consequences of the second.


Edited by Seira (18/03/2017 15:11)

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#1413220 - 18/03/2017 20:06 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
Originally Posted By: Seira
14th to 24th of March, 2017:
Potential Key features:
  • This potential [cut-off] system is capable of gaining more latent energy from the tropical north (Broome-GOC-NE QLD-NSW), intensifying pressure and temperature gradient at its core, both vertically and horizontally.
  • Flooding is a potential issue (consequence of this) along the NSW northern Coastal Fringes within this time period, as Coral-Sea moisture ventures south.
  • The troposphere, in this situation, would be fairly unstable with cooler-to-colder air above a milder-to-warm, humid air-mass.

More Flood Warnings now issued by Bureau.

Clarity: mesoscale cut-off near Eastern Seaboard is a precursor.


Edited by Seira (18/03/2017 20:16)

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#1415673 - 26/03/2017 00:06 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
Bowen QLD might need to prepare for flooding next 3-5 days... frown just my view, oh well smile .

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#1415921 - 26/03/2017 13:32 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
Originally Posted By: Seira
Bowen QLD might need to prepare for flooding next 3-5 days... frown just my view, oh well smile .

"Areas of heavy rain with the potential to cause severe flash flooding are expected to develop about parts of the northern and central Queensland coast and adjacent inland areas late on Sunday and continue through Monday and Tuesday."

Source: Bureau.

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#1418996 - 29/03/2017 16:54 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
Originally Posted By: Seira
Originally Posted By: Seira
Bowen QLD might need to prepare for flooding next 3-5 days... frown just my view, oh well smile .

"Areas of heavy rain with the potential to cause severe flash flooding are expected to develop about parts of the northern and central Queensland coast and adjacent inland areas late on Sunday and continue through Monday and Tuesday."

Source: Bureau.

Several streamflow sites now at major flood classification level in the region...some continuing to rise (e.g. Mt Bridget TM, SW of Mackay) frown eek !

[544 mm in 24 hours at Undercliff (533126) TM shocked .]

Source: As above (Bureau).

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#1419028 - 29/03/2017 18:00 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
Originally Posted By: Seira
Several streamflow sites now at major flood classification level in the region...

Warnings issued accordingly.

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#1419549 - 30/03/2017 13:29 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
Originally Posted By: Seira
Originally Posted By: Seira
Several streamflow sites now at major flood classification level in the region...

Warnings issued accordingly.

Warnings Warranted...Situation is becoming decidedly serious with system venturing further south, dumping 100s of mm SW of Brisbane frown , further falls on now already-affected areas!!!

[For anyone reading these notes (in affected areas), I strongly suggest following the Bureau's advices and warnings, observations and stream levels carefully smile .]


Edited by Seira (30/03/2017 13:36)

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#1419907 - 30/03/2017 20:18 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
Very significant (major) flooding in the Logan and Albert River Catchments SW of Brisbane shocked frown !!

Source: Bureau warning notes.


Edited by Seira (30/03/2017 20:25)

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#1420833 - 05/04/2017 22:32 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
The following is based on the period 14th to 24th of March (previously indicated), prior to the formation of STC Debbie (about the 27th), which seemed to be associated with Monsoon Trough activity (initially) in the Coral Sea, around the same time. That event has been adequately covered in the appropriate threads, for better or worse.

Written 12.40 pm ACDT, Sunday 19th of March 2017:
Winds potentially from the N-NE. Moisture getting pumped down the Eastern-Seaboard via Coral Sea, across the 576-thickness contour. Meaning it’s crossing from higher-temperature and pressure to lower-temperature and pressure regions = more cloud-cover and less volume to retain moisture in the air. Likely to rain out. Add orographic effects from elevated Great Dividing Range to that and there is a recipe for HP thunderstorms/embedded with showers/rain. With dew-points 14-16 C or more across Central NSW (near-surface temperatures 24-26), not good for regions N-NE of Melbourne. Also, a risk of HP cells east of Adelaide Hills as surface troughing wraps around from the S-SE. 700-hPa RH humidity is higher east of Eastern (Mt. Lofty) Range slopes. Very shallow upper-low south of Adelaide = possible heavy falls (see below).

Potential widespread showers/rain
(supported by Bureau 4-day forecast maps, starting 10 pm, 20th of March).

Observations (Collated 22nd of March, 8.20 pm ACDT), Unless Otherwise Indicated.

Echo Hills Alert, 535085 [QLD]: 96 mm, 24 hours. *
South Lesdale Alert, 544029 [QLD]: 57 mm, 24 hours. *
Bourke [NSW]: 31 mm, 24 hours to 9 am, 20th of March.
Cobar [NSW]: 19 mm, 24 hours to 9 am, 21st of March.
Wanganella Gen. Store [NSW]: 57 mm, 24 hours to 9 am, 22nd of March.
Yarrawonga [VIC]: 11 mm, 24 hours to 9 am, 22nd of March.
Mt. Hotham [VIC]: 33 mm, 24 hours to 9 am, 22nd of March.
Echuca [VIC]: 15 mm, 24 hours to 9 am, 22nd of March.
Kanagulk AWS [VIC]: 25 mm, 24 hours to 9 am, 22nd of March.
Melbourne [VIC]: 9.2 mm, 24 hours to 9 am, 22nd of March, highest southwest (100+ mm) and east.
Portland [VIC]: 31 mm, 24 hours to 9 am, 22nd of March.
Smithton Aero [TAS]: 14 mm, 24 hours to 9 am, 22nd of March.
Mt. Gambier [SA]: 5.8 mm, 24 hours to 9 am, 22nd of March.
Adelaide [SA]: 26.8 mm, 24 hours to 9 am, 21st of March.
Harris Rd [WA]: 70 mm, 24 hours to 9 am, 22nd of March.
Albany [WA]: 17 mm, since 9 am, 22nd of March.

All stated observations contributed to soil moisture or run-off.

* Dates Missing, unable to be checked (rainfall amount known).

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#1421087 - 09/04/2017 11:12 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
Melbourne (VIC) may get another 30-50 mm in the next 24-48 hours (to the 11th of April), with a polar-maritime air stream in addition to that already received to 9 am this morning (Melbourne time).
Source: ACCESS-R.


Edited by Seira (09/04/2017 11:15)

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#1421202 - 09/04/2017 23:51 Re: Streamflow Observation [Re: Seira]
Thunderstruck Offline
Lightning man

Registered: 10/05/2001
Posts: 14798
Loc: Seaford Meadows, SA
I read these mate all good!! very impressive wrap around rainband atm, very cold uppers and strong moisture convergence and uplift training in an area for a long time = big flood potential. Convective lines embedded in the main rainband as well adding to the intensity.

TS cool

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#1421305 - 10/04/2017 22:25 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
There doesn't seem to have been any significantly observable/measurable flooding in the area -- according to the flow-meters in the region -- so there is nothing of that to report. There is, however, a stat of 100 mm recorded at Durdidwarrah (site 87021) in the 24 hours to 9 am VIC time, surrounded by widespread 50-99 mm falls to the west of Melbourne...probably contributing significantly to soil moisture.

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#1421604 - 16/04/2017 13:18 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
Potential 20-40 mm rainfall event between about the 19th and 21st of April, extending north-south from about 30 degrees South to Mt. Gambier, SA.

[A middle-to-upper level disturbance on the axis of an Indian-Ocean NW moisture in-feed, crossing the 576-thickness contour. Pressure may trough (dip) slightly, late on the 19th.]


Edited by Seira (16/04/2017 13:23)

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#1421871 - 20/04/2017 19:40 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
Approximately mid-way through the system (19th-21st), 18-19 mm so far smile .

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#1422003 - 23/04/2017 17:26 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6778
Loc: Adelaide Hills.
Highest 24-hour fall to 9 am 21st of April 2017: 103 mm at Woomelang, VIC; widespread 25-50 mm, Western VIC. Great falls for the Riverina smile !


Edited by Seira (23/04/2017 17:28)

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