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#1397504 - 17/12/2016 21:20 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 6842
Loc: Adelaide Hills.
10-20 mm recorded in the Northern Flinders Ranges to 9 am, 15th.
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#1398052 - 21/12/2016 20:40 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 6842
Loc: Adelaide Hills.
Originally Posted By: -Cosmic- (naz)
Rewritten 8:35 pm ACDT:
It seems the southern-ocean 500-hPa troughs have been aligning to the north-eastern flank of the west-coast surface ridge, bringing with them milder temperatures due to travelling so far north (they gain latent heat), ...in the process they seem to be destabilising the northern thickness plumes (generating pressure gradients) and increasing mixing. 21.2 mm in 32 hours to 8 pm, 8th, not isolated stuff going by the area map for SA. There may potentially more on the way. A rough calculation gives:
Vapour pressure: 22.4 hPa (32/22, max-min Tuesday)
Dewpoint: 19.3 C
Surface barometric pressure: 995 hPa
Precipitable-Water: 25-40 mm.

The reference below may also help smile .
-------------------------------------------------------------

Post #1245515 - 03-03-2014 11:27 PM:

HypothesisIs Southern Australia becoming more Humid Sub-tropical?

And now for part 2:

Notes -- Probable Rain Event 27th-29th of December 2016:

Written 18th of December 2016:
There is a chance a shallow upper (500-hPa) trough will drift across the Southeast of SA (south of about 33-to-34 degrees latitude; Ceduna, SA) overnight Monday into Tuesday (20th of December). A moderately strong ridge skirting SW WA (near Perth-to-Albany) is again being compressed – from the north and south. The northern compression involves the development of tropical features…venturing south from near Java. These include strengthening cyclonic activity and higher 500-1000 mb thickness plumes extending from Geraldton WA, to approximately Alice Springs. The strengthening cyclonic activity may significantly influence the direction and flow of [middle-level] moisture, dragging it away from the continental interior towards the WA coastline. This implies a possible convergence of moisture (surface to 700 hPa) between Geraldton, WA, and Alice Springs, NT (i.e. Ngaanyatjarra-Giles, WA). As the temperature profile is first stronger north-south (in the eastern interior) then north-south (in the western interior), this suggests more latent heat will be moving west rather than east across interior, feeding into the cyclonic activity. Where the stronger troughing is (Darwin to Geraldton) this can generate erratic wind direction changes, and compress the isobars running parallel. This, I think, is a recipe for increased storm activity near the WA/SA/NT border intersect.

Written 19th of December 2016:
As the cyclonic activity moves down the northern WA coast, towards Broome then Geraldton, it is likely to destabilise ridging in the region (NE-SW WA coastal fringes). This can give rise to more surface- and middle-level troughing (surface to 700 hPa), subsequently changing the wind direction and movement of moisture. During this time, it is likely the pressure-gradient force on the western edge of the cyclonic activity (Eastern Indian Ocean) will be greater than the Coriolis Effect (cooler ocean water, warmer inland). Additionally, the cyclonic activity seems likely to drag warm, drier air from the edge of the 500-1000 mb plume (Alice Springs vicinity) across the region where south-westerly winds have been more prevalent (Eucla, WA), thus reducing temperatures, and increasing precipitable-water. This wind-change dynamic has the capacity to drag lows and troughing inland towards SA as the central interior becomes cooler and more conducive to moisture build-up.

Written 20th of December 2016:
Places likely to be affected by this cyclonic-upper trough-inland wind and moisture dynamic would be those in the central south-western quadrant and Southeast of the country (i.e. Ceduna-Adelaide, SA). As the 500-100 mb thickness difference – temperature- and kinetic energy-gradient – increases with a [500-hPa] shallow-to-moderate upper trough intersecting 70-90% RH 700-hPa cyclonic moisture somewhere between Albany and Ngaanyatjarra-Giles, hot-to-very-hot winds would drift west from near NE SA. High-precipitation under extensive cloud-cover (severe thunderstorms, embedded with a rainband) seems likely to affect the Western-Central SA. Falls of 20-40 mm seem likely, isolated 50-100. It is difficult to tell how far the 700 hPa moisture can drift east before the impact of inland warmth becomes telling. One thing is telling though with both ACCESS and GFS models – the thickness gradient SW-NE is impressive for the 27th-28th:

Attempted Forecast Variables for the 28th of December 2016, Ceduna-Adelaide, SA (21st):
Dewpoint 22-24 C;
Air Temperature Max/Min 33/21 C.
Pressure: ~ 989 hPa.
Precipitable-water: 60-80 mm.
Sultry, thick cloud; CAPE 1200 J/Kg; CINH -250 J/Kg.
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#1398856 - 27/12/2016 11:30 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Loc: Adelaide Hills.
80-90% confident of river rises to near/greater than minor flood level late 28th-early 29th of December 2016...east of a line Ceduna-Adelaide, SA!!
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#1398875 - 27/12/2016 14:15 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
Originally Posted By: -Cosmic- (naz)
One thing is telling though with both ACCESS and GFS models – the thickness gradient SW-NE is impressive for the 27th-28th:

The 576 thickness is likely to be around half way between the tropical feature travelling south, and the more south-westerly system.
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#1399279 - 29/12/2016 13:07 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
Woodsides annual rainfall record probably shattered, power out since 3 to 4 am yesterday not due till 8.15 pm, river almost minor 28th. Highest 6 hour rainfall that i know of. 891 am emergency radio broadcaster from nsw, what the....shocking winds during low peak. Forgot to mention....Damage.


Edited by -Cosmic- (naz) (29/12/2016 13:09)
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#1399408 - 29/12/2016 22:49 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
This is a bloody waste of time...unless someone else has had in excess of 36 hours without power, and wants to talk about what caused it, bye!
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#1399424 - 30/12/2016 01:06 Re: Streamflow Observation [Re: Seira]
bundybear Offline
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Registered: 28/12/2010
Posts: 2012
Loc: Between Bundy and Gladstone
Originally Posted By: -Cosmic- (naz)
This is a bloody waste of time...unless someone else has had in excess of 36 hours without power, and wants to talk about what caused it, bye!


If I remember rightly in the last big flood we had here we were without mains power for 5 days. No phone for about 3 weeks. No mobiles for a week and a half unless you got lucky.

It took the council 3 days to realise there was even something wrong in the area as we are at the butt end to them and whilst they had rain we had flood.

After that it took them a couple of months to fix the bridge which was our route to town. Either had to head to the town to the north or take the very long way which is about 3 hours.

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#1399489 - 30/12/2016 15:08 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
So you empathise with people affected by the recent SA power outage/severe weather?


Edited by -Cosmic- (naz) (30/12/2016 15:11)
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#1400838 - 06/01/2017 15:22 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 6842
Loc: Adelaide Hills.
Monthly Rainfall, Estimated Flow:- Northern Woodside, 2016 (in mm).
Month, (Highest Daily, Date), Estimated Streamflow Peak, Old [2013] Model (metres).

Jan-16 61.9, (32.5, 29th), 1.055.
Feb-16 22, (20.8, 2nd), 0.796.
Mar-16 38.9, (18.5, 10th), 0.635.
Apr-16 16.2, (6.6, 29th), 0.246.
May-16 182.3, (77.2, 7th), 2.564.
[9th of May river started filling from scratch due to pasture run-off.]

Jun-16 125.8, (32, 23rd), 1.218.
Jul-16 239, (34, 26th), 1.868.
[July--Highest monthly rainfall since January 2010.]

Aug-16 86.6, (16.7, 19th), 0.680.
Sep-16 208, (53.2, 29th), 2.285.
Oct-16 158.9, (38.3, 3rd), 1.759.
Nov-16 31, (11.6, 10th), 0.540.
Dec-16 133.2, (84, 28th), 2.885.
[Dec 28th--Quickest river rise observed since estimated records began.

Estimates Dec:

25th--0.04 m.
26th--0.20 m.
27th--0.36 m.
28th--2.89 m.
29th--1.74 m.

Actual Dec: BoM.

25th--0.05 m.
26th--0.29 m.
27th--0.08 m.
28th--1.74 m.
29th--0.29 m.]

Annual Rainfall: 1303.8 mm.
Average Annual Rainfall: Unknown for area, nearest longer-term official gauge 800-860 mm, 23829 (BoM).
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#1401440 - 10/01/2017 21:35 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
8th of January 2017:
The next potential date-ranges for reasonable (10+ mm) rain-bearing weather in an area Port Lincoln-Hawker-Renmark-Cape Jervis SA maybe the 12th-14th, and 17th-19th [of January]. Falls exceeding 10 mm have already been recorded in the state’s Mid North 9 am to 6 pm, 9th, in a precursor event.

12th-14th:
Estimated Max/Min: 25/21. Dewpoint: 15-20 degrees C.
Estimated Surface Barometric Pressure: 990 hPa.
Estimated Precipitable-Water: 20-40 mm.
Cloudy-to-Overcast (thick nimbostratus, stratus, cumulus).
Estimated rain-range: widespread 15-20 mm.

Estimated run-off impact: slight-to-mild [0.64 with 20 mm, up from 0.04].

17th-19th:
Estimated Max/Min: 21/15. Dewpoint: 8-15 degrees C.
Estimated Surface Barometric Pressure: 1000 hPa.
Estimated Precipitable-Water: 25-45 mm.
Partly cloudy-to-cloudy (stratus, cumulonimbus, altocumulus).
Estimated rain-range: unknown, possibly in a narrow band of activity.

Estimated run-off impact: unknown, dependent on the events of 12th-14th [minor flooding requires ~ 62 mm in 24 hours assuming 20 mm from the previous event].
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#1401700 - 12/01/2017 15:25 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 6842
Loc: Adelaide Hills.
Originally Posted By: -Cosmic- (naz)
8th of January 2017:
The next potential date-ranges for reasonable (10+ mm) rain-bearing weather in an area Port Lincoln-Hawker-Renmark-Cape Jervis SA maybe the 12th-14th, and 17th-19th [of January]. Falls exceeding 10 mm have already been recorded in the state’s Mid North 9 am to 6 pm, 9th, in a precursor event.

12th-14th:
Estimated Max/Min: 25/21. Dewpoint: 15-20 degrees C.
Estimated Surface Barometric Pressure: 990 hPa.
Estimated Precipitable-Water: 20-40 mm.
Cloudy-to-Overcast (thick nimbostratus, stratus, cumulus).
Estimated rain-range: widespread 15-20 mm.

Estimated run-off impact: slight-to-mild [0.64 with 20 mm, up from 0.04].

Higher probability of moderate run-off - 1.1 to 2.1 metres.
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#1401704 - 12/01/2017 15:46 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
Anything more than about 63 mm in less than 24 hours and there looks to be a strong chance of low-lying flooding (modelled) in the Central Adelaide Hills of SA.
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#1401976 - 13/01/2017 19:34 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
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Loc: Adelaide Hills.
Originally Posted By: -Cosmic- (naz)
12th-14th:
Estimated rain-range: widespread 15-20 mm.

Estimated run-off impact: slight-to-mild [0.64 with 20 mm, up from 0.04].

12.7 mm to 7 pm from 12 am. Not bad considering highest local falls were 20-30 mm smile . Minimal run-off.


Edited by -Cosmic- (naz) (13/01/2017 19:36)
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#1402924 - 18/01/2017 19:29 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 6842
Loc: Adelaide Hills.
Originally Posted By: -Cosmic- (naz)
Originally Posted By: -Cosmic- (naz)
12th-14th:
Estimated rain-range: widespread 15-20 mm.

Estimated run-off impact: slight-to-mild [0.64 with 20 mm, up from 0.04].

12.7 mm to 7 pm from 12 am. Not bad considering highest local falls were 20-30 mm smile . Minimal run-off.

Minimal run-off estimate was 0.26 metres (the model underestimates stream flow peaks and overestimates troughs).

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

Some additional insight into why I thought the 12th-14th of January 2017 would be a light-to-moderate rain event, and why the 17th-19th (maybe now 18th-20th) could be more unknown:

Written 8th of January 2017 [Updated 9th]:
In addition to:

Quote:
Notes: 24th of November 9:10 pm ACDT [Updated from 23rd, 8:30 pm]

Extensions (and descriptive excerpt to the 18th of January):

Quote:
There now appears to be a persistent plume of higher 500-1000 mb thickness air from the tropics (Broome-Darwin region) migrating S-SE into the Australian continental interior, which is not only driving interior temperatures up due to sensible heat, but pushing the northern edge of the west-coast ridge, south – compressing it as it drifts east.

Quote:
This will not cause [cold]* fronts to buckle because the western, drifting ridge (which narrows north-south when it reaches the higher thickness) is weakened [west-east, the winds become more variable than for under the influence of a strong ridge]*.

Quote:
The NW-SE troughing and diffuse regions of tropical lower-pressure disturbance across the interior are able to interact with the southerly upper trough [next one perhaps by the 10th of January, with the main long-wave upper rossby-wave]*.

Quote:
700-500 hPa winds and moisture from the south may contribute to this by anchoring (at 500 hPa) in the NE region of the compressed ridge. This is also a mechanism for tropical (700 hPa), interior moisture to drift down, hitting a large temperature gradient [SW-NE]*.

Quote:
Compression means the pressure-gradient force [stronger, more variable winds]* becomes greater than the Coriolis Force/Effect [calmer, more settled conditions]*. This can induce troughs [see next quote below]*.

Quote:
These are humid sub-tropical conditions. The western ridging is acting as a catalyst [for trough formation, by allowing 700 hPa – low-to-middle level – moisture to converge near the 576 thickness interface]*.

Quote:
Written 18th of December 2016:
[…]
As the temperature profile is first stronger [with more sensible heat]* north-south (in the eastern interior) then north-south (in the western interior), this suggests more latent heat [for forming clouds]* will be moving west rather than east across interior [Clausius Statement of the 2nd Law of Thermodynamics]*, feeding into [...] [low/trough]* activity [nearer the West Coast]. Where the stronger troughing is (Darwin to Geraldton) this can generate erratic wind direction changes, and compress the isobars running parallel [lead to variable troughing and changes in wind direction where compression occurs]*.

Quote:
Written 19th of December 2016:
As the […] [low/trough]* activity moves down the northern WA coast, towards Broome then Geraldton, it is likely to destabilise ridging in the region (NE-SW WA coastal fringes). This can give rise to more surface- and middle-level troughing (surface to 700 hPa), subsequently changing the wind direction and movement of moisture [more S-SE than SE]*. During this time, it is likely the pressure-gradient force on the western edge of the […] [low/trough]* activity (Eastern Indian Ocean) will be greater than the Coriolis Effect (cooler ocean water, warmer inland). Additionally, […] [this]* activity seems likely to drag warm, drier air from the edge of the 500-1000 mb plume (Alice Springs vicinity) across the region where south-westerly winds have been more prevalent (Eucla, WA), thus reducing temperatures, and increasing precipitable-water. This wind-change dynamic has the capacity to drag lows and troughing inland towards SA as the central interior becomes cooler and more conducive to moisture build-up.

Written 8th of January 2017 [Updated 9th]:
In the case of the approaching NW-SW thickness-plume-upper-trough interaction (around the 13th of January), the change in wind speed to the west and south of West Coast low and/or trough formation [10th of January] can bring a mild 500-hPa plume from the south to interact the with a 500-1000 mb thickness plume (shifting towards SW WA, from about Geraldton). This interaction seems likely to pick up moisture in lower- and middle-levels of the troposphere as it drifts east – as the [southern] upper-trough (which is not embedded) meets the southern axis of the northern thickness plume (with the ridge to the immediate west). It will likely gain more ocean wind stress and momentum (because the surface-to-500-hPa temperature-gradient will be stronger, land-to-water). However, this can be tempered by the weak surface ridge over which the 500-hPa upper trough arcs to reach northeast. Surface trough activity is not unlikely between the two.

Of more interest rainfall-wise (though further out, the 18th of January) is an embedded upper trough in the main Southern-Ocean rossby-wave, which becomes annexed, capable of bringing heavy falls inland, Adelaide-Hawker-Renmark, SA. This is a fair way out, but noteworthy I think. This embedded upper 500-hPa would be unlikely without the main Southern-Ocean rossby-wave travelling west-east near the 13th.

Underline, []* Added. […] Removed.

Revision:
18th-20th:
Estimated Max/Min: 20/12 (18th), 31/14 (19th), 23/16 (20th).
Estimated Dewpoints: 8-15 degrees C (~ 14.5 (18th), 13.5 (19th), 16 (20th)).
Estimated Surface Barometric Pressure: 998-1004 hPa.
Estimated Precipitable-Water: 18-141 mm* (~ 51 average).
Partly cloudy-to-cloudy (stratus, cumulonimbus, cirrus, altocumulus).
Estimated rain-range: anything up to 50-60 mm (entire period).

*Possibly in a narrow band of activity. Please note falls may be heavily-dependent on where and when any rainbands/thunderstorms form.

Estimated run-off impact: 1.26 m (60 mm).
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#1405153 - 03/02/2017 17:21 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 6842
Loc: Adelaide Hills.
Attempted Dynamic Weather Forecast: 28th of January to 8th of February 2017:
Variables:
Wind direction, Max/Min, Dewpoint, Rain Probability:
S-SE, 23/10, 9, Medium (20-60%) (afternoon, 28th).

There is a [surface] ridge in the Bight; a [surface] ridge in Eastern IO disrupted by lower-pressure system moving in a south-westerly direction. Inland WA troughing north of the 576-thickness is forcing winds off the equatorial-originating low [moving towards the S-SW] to interact with those related to a shallow upper-to-middle level (UML) trough moving up from the SW [between Eastern IO ridge and the one in the Bight]. The dewpoints with the winds coming down through the WA interior are much higher than those associated with the UML trough (below the 576-line), hence a strong indication of much higher inland WA absolute humidity in comparison. The thickness gradient (N-S) has a greater capacity for moisture to be retained inland (to the east of the migrating lower-pressure system) than with the SW UML trough. The wind-direction between these two features is around the spiralling low, towards the UML trough, which could form an arc of winds – S, to SW, to W, to NW – north of Perth (WA). The thickness [temperature] gradient means the moisture from inland WA can be directed towards the lower thickness region to the south of the 576-thickness line, which implies it could rain out (eventually), Geraldton-Perth-Albany-Eucla, in coming [28th-31st] days. The disruption of the Eastern IO ridge [by the migrating low] also implies the Southern-Ocean rossby-wave may compensate by allow more [shallow] UML troughs to reach Central SA.

As more UML troughs reach Central SA shores [due to the SW-migrating low in the Eastern IO], the higher-pressure system in the Bight can be disrupted in such a way as to allow a more dynamic, trough-based patterns to emerge. The displacement of the ridge in the Bight implies another ridge will attempt to take its place, from the west, in the process itself becoming compressed between the 576-line and tropical plume over the interior [WA/NT]. As UML troughs continue passage through (above the surface ridge in the Bight, in vertically), there may come a point when their arcing, and the changing in the 576-line, meets the very humid, warm air from the north [interior], bringing heavier falls to Ceduna-Port Wakefield-Nuriootpa-Loxton-Ouyen.

Written 31st of January 2017:
4th-8th of February 2017:.
Estimates (Adelaide Hills):
Date: Winds, Moisture Source, Max/Min, Dewpoint, Rain Probability (%).
4th, S-SW, Tm-Sm, 25/7, 4.3, Medium (20-60%).
5th, S-SE, Sm-Pm, 23/13, 12.4, High (60%+).
6th, SE, Pm-Tm, 23/9, 7.7, Medium (20-60%).
7th, ESE, Tm, 25/13, 12.2, High (60%+).
8th, E-ENE, Tm-Tc, 27/13, 12, Medium (20-60%).

Tm: Tropical Maritime.
Sm: Southern Maritime.
Pm: Polar Maritime.
Tc: Tropical Continental.

Estimated Surface Barometric Pressure: 1007 hPa.
Estimated Precipitable-Water: 12-35 mm on high probability days (~ 22 average per day).
Cloudy-to-overcast (stratus, embedded cumulus, nimbostratus, cirrus, altocumulus).
Estimated rain-range: anything between 30-50 mm (entire period), isolated 50-80.
700-hPa winds, Relative Humidity: Westerly, 70%+.

Surface run-off impact: minimal-to-slight, mostly soil moisture [although this depends on the rain-rate].
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#1405776 - 06/02/2017 18:42 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 6842
Loc: Adelaide Hills.
38 mm, 12 am, 5th of February to 6 pm, 6th. Owen further in NW had 52 in 24 hours smile . Totals smaller further NE and SE. Not entire period over yet though.


Edited by -Cosmic- (naz) (06/02/2017 18:44)
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#1409072 - 21/02/2017 21:38 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 6842
Loc: Adelaide Hills.
Bureau: As of 19th, 9 am, to 20th, 9 am, or later (2-3 days)

McArthur River Borroloola (514700, NT):
216 mm (24 hours) to 9 am (19th).
90 mm to 9 am (20th).
34 mm since 9 am, 20th (6.7 hours).
340 mm total (54.7 hours).
Minor Flood Level Exceeded (34.7 hours).

Roma AWS (43091, QLD):
28 mm (24 hours) to 9 am, 19th (local time).
29 mm since 9 am (10.5 hours).
57 mm total (34.5 hours).

Durah Homestead AL (542010, QLD):
36 mm (24 hours) to 9 am, 19th.
28 mm since 9 am (10.7 hours).
64 mm total (34.7 hours).

Strahan (97072, TAS):
37 mm (24 hours) to 9 am, 19th (local time).
Low Rocky Point AWS (TAS):
43 mm (24 hours) to 9 am, 19th.

No discernible changes in local surface run-off apparent (QLD, TAS).
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#1410644 - 03/03/2017 22:48 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 6842
Loc: Adelaide Hills.
It might be worth taking a closer look at Wollongong area's (NSW) forecast for the next 2 days, if you live in the area (from the Bureau).

Also:
Issued at 11:00 am EDT on Friday 3 March 2017.
FLOOD WATCH FOR THE MORUYA, BEGA AND ST GEORGES BASIN RIVER VALLEYS

And:
Rainfall (mm):
Last 24-48 hours (and 7 days to current):

Mount Kembla: 66 (110).
North Macquarie: 50 (118.5).
Port Kembla: 42 (121.5).
Rixon Pass: 78 (203).
Upper Calderwood: 63 (131).

Severe Weather Warning Issued for Heavy Rainfall.

[All for NSW].


Edited by -Cosmic- (naz) (03/03/2017 22:55)
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#1410771 - 04/03/2017 20:05 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 6842
Loc: Adelaide Hills.
Notes: Written 3rd of March [Minor Grammar Check 4th]:
The 1012 hPa upper/surface low (3rd of March, 5 pm AEDT) combination running at approximately 90 degrees to the NSW coast near Wollongong is associated with a surface trough which has formed (arced off) a passing front, travelling at 45 knots east, across New Zealand. The ridging across the Bight and to a lesser extent across Tasmania is generating a gap down the western Tasmanian coast. This gap is enabling the low/s to drag milder wind-streams from the westerlies (-12 to -14 C at 500-hPa), north into the interior (VIC/NSW). At the same time, much higher dewpoint winds (adjacent to NSW) from the east (Pacific Ocean) appear to be siphoning into the surface low (22-24 C at the surface). This can give a land-sea breeze affect wherein cooler SSTs winds ascend over warmer, elevated terrain, generating orographic uplift. The rising, cooling, humid air is forced to condense, forming clouds, which then back-fill towards the sea (at increasingly higher elevation). Having a higher-pressure system [ridge] between Tasmania and New Zealand provides an outlet for the higher-elevation, cooler, drier winds.


Edited by -Cosmic- (naz) (04/03/2017 20:06)
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#1411907 - 12/03/2017 21:04 Re: Streamflow Observation [Re: Seira]
Seira Offline
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Registered: 27/08/2003
Posts: 6842
Loc: Adelaide Hills.
7th to 13th of March, 2017:

My understanding (scenario):

Ex-TC Blanche (from 11 am AEDT, 5th to 11 pm AEDT, 6th of March) [Bureau maps], formed near GOC/Darwin NT, moving towards Broome (WA). Ex-TC Remnants – surface low – moved down WA coast, dissipating along the way, yet generating enough disruption of the significant Coriolis Force [near Perth WA] (the higher-pressure ridge), to interfere with the high’s [eastern flank] wind streams in the Eastern Indian Ocean. This interference allowed the higher-pressure to buckle (make way for a cut-off upper-trough) forming closer the centre of the Bight. This was partly because the Indian Ocean high was disrupted by the Ex-TC remnants, and partially due to ridge compression.

The cut-off reaches the blue thickness line (540) at 500 hPa, and is able to venture further north (between Albany and Eucla WA), before the high in the west starts to affect it more (move east). The fact the 540-thickness is reached suggests the upper trough has momentum and vertical energy, with the atmosphere being fairly unstable. The buckling ridge is then able to feed (itself) from the southern Bight. The Ex-TC dissipated, the moderate-strength middle-to-upper trough surges up further towards Eucla (WA) from the SW on the axis of the buckling ridge [NW-SE]. This cut-off seems to have stronger upper winds in the east, right next to the migrating ridge. It is clearly visible on the 500 HGHT anomalies, with more disturbances occurring on the upper 500 HGHT anomalies on the SW-NE axis, through the Bight, approaching Adelaide SA.

The moderate-strength upper-trough gets cool-enough so as to draw higher-dewpoint winds from the Coral Sea, near the surface [surface low and troughing forming].

Yesterday/Today Bureau was/is saying 8 to 20 mm locally (for Sunday), with 90% change (of any rain).

…speaking of which we exceeded the 8-mm mark as of about 3 pm smile .
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