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#1012326 - 15/09/2011 12:18 Sth WA: Cold fronts and windy conditions 17th-23rd September 2011
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Looks like a great burst of wintry weather ahead, both cold fronts on Sunday and next Wednesday are predicted to have good southerly pushes behind them, be interesting to see how that turns out. One of the models also hinting at a cut-off low with a bit of a cold pool behind it for next Wednesday, something to watch. smile

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#1012327 - 15/09/2011 12:21 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Quote:
Frequent fronts top up rainfall totals in the west
Alex Zadnik, Thursday September 15, 2011 - 08:48 EST

After the wettest winter in eight years, Perth is in for a healthy dose of spring rainfall in
coming days, particularly on Sunday.

Perth has had a tough run in the rainfall stakes over the last decade but the winter just
past provided a more positive story. While the rainfall total of 448mm was still a little
short of the long-term winter average of 479mm, it was the best result in eight years for
the city. Last winter was especially dry with just 256mm. The winter of 2006 was a horror
season, with a new record low of 230mm.

The good news this year though is that our healthy winter rains have spilled over into the
spring season and should continue over coming days, with frequent cold fronts bringing
some benefit to the Lower West and Southwest.

The strongest cold front and heaviest rainfall looks like reaching these districts on Sunday
but showers are on the forecast for the next 4-5 days. 15-25mm accumulated totals are
likely for Perth and the Lower West by Monday, with the bulk of this falling on Sunday.
However, the showers do look like holding off for the AFL Final on Saturday evening.
Heavier 25-50mm totals are likely for the Southwest district by Monday.

- Weatherzone

Weatherzone 2011

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#1012366 - 15/09/2011 16:03 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
snowbaby Offline
Weather Freak

Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
The cold pool on sunday not quite as promising as wednesday's. Last night's ecmwf didn't show much behind sunday's but is more in tune on the other. GFS has 850 temps as low as 3 or 4 below for wednesday - would have to be the lowest this year if it comes off? Dont like to say much - scared I'll jinx it! but nice to see we might have a day or so of decent southerlies!


Edited by snowbaby (15/09/2011 16:09)

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#1012370 - 15/09/2011 16:24 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: snowbaby]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Strange how GFS has the 850's looking awesome for Wednesday, even the 700's look great, but 500's are only at -23 or so. Watching this one but I have a feeling within a few days, the models will have downgraded it completely. frown

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#1012386 - 15/09/2011 18:13 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Getting quite a decent shower here and Perth radar showing scattered moderate showers around the metro area. Perth at 2.8mm since 9am. Mandurah has copped a decent showers, 8.8mm since 9am. grin

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#1012439 - 16/09/2011 08:12 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
snowbaby Offline
Weather Freak

Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
I haven't got a raingauge so I'm not sure how much we had last night but there were a few very heavy showers. The airport is reporting 3-4 mm. I would've thought we got more than that here in town - just from the sound on the roof. Got any figures to confirm Big_Pete?

Though sometimes hard to pick because it only does 12 hourly runs for our region, ecmwf does seem to have gone off idea of cold pool next week at this stage and GFS - whilst it does still have a period of subzero 850 temps there doesn't look like a lot of moisture around when it kicks in.

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#1012452 - 16/09/2011 10:06 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: snowbaby]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Yeah it really poured here last night around 10pm, didn't last long here (Bayonet Head), but geez it was heavy. I can see there's 5mm in my guage, but have to wait until 9am to see what you got in town.

I didn't think GFS would hold up about Wednesday, Sunday's cold pool looks better now, 500mb temps at -29C and 850mb temps at 0C. Doubt snow being too likely at this stage, but might see a few thunderies and hail. smile

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#1012471 - 16/09/2011 12:05 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Town only got 3mm. shocked confused

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#1012501 - 16/09/2011 13:40 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Tonight's predicted sounding looks awesome! grin


We've already gone above the predicted max of 19 degrees, now 20.9 degrees at my place. The more heating the better, because that feature behind the coming front looks promising. grin

Quote:
Forecast for Friday
Showers tending scattered southwest of a line Perth to Ravensthorpe with isolated
afternoon and evening thunderstorms possible about southern coastal parts of the
Southwest district and the adjacent South Coastal district.


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#1012508 - 16/09/2011 14:01 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Cells building rapidly to my northeast, bring it on! Even the 12pm soundings show pretty unstable conditions. grin

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#1012542 - 16/09/2011 16:07 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Lightning over Walpole and North Walpole has just recorded a gust of 91km/h. shocked

http://www.weatherzone.com.au/wa/southwest/walpole

Quote:
UPDATED FORECASTS FOR WESTERN AUSTRALIAN PROVINCIAL TOWNS
Issued at 1:03pm WST on Friday the 16th of September 2011
for today and tonight
ALBANY:
Few showers, thunderstorm risk. Moderate to fresh W/NW winds
.
grin

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#1012561 - 16/09/2011 18:22 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Had a thunderstorm this arvo, I captured my best shot so far. Camera was a bit blurred, because of heavy rain, got 11mm from the thunderstorm. grin
Will post full video later. grin

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#1012585 - 16/09/2011 21:23 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Had some showers after the storm, including some hail. More lightning to my northeast. grin
Quote:
ALBANY:
Remainder of Friday: A few showers, with the risk of a thunderstorm and possible
hail.
Fresh W/SW winds.
Saturday: Partly cloudy with the chance of a light shower from late evening.
Moderate to fresh W/NW winds, strengthening in the afternoon.

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#1012587 - 16/09/2011 21:40 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Coldies to the south and east are going nuts! Lightning everywhere! Glad its at a reasonable distance, lol! grin

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#1012591 - 16/09/2011 21:56 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
snowbaby Offline
Weather Freak

Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A

I didn't think GFS would hold up about Wednesday, Sunday's cold pool looks better now, 500mb temps at -29C and 850mb temps at 0C. Doubt snow being too likely at this stage, but might see a few thunderies and hail. smile [/quote]

No I dont think there's much hope for the s word - the 500's and 700's are really good for a period on Sunday but at 850 less so and I'd say it'd be too warm at levels nearer the ground level - unless there's a local fluky event. The instability is looking pretty good tho.

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#1012619 - 17/09/2011 09:17 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: snowbaby]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Yeah GFS now predicting 500's of -29C and 700's of -10C. 850's are only 1C. I'm going to forget the s word and look forward to some more thunderstorms and hail with this front.
Shear looks great though, around 15k knots at the surface and 57 knots at 900mb! shocked

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#1012621 - 17/09/2011 09:22 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Me thinks GFS has over estimated the moisture. Look at this predicted sounding for Sunday afternoon:


Practically the whole atmosphere is saturated up to around 350mb! Surely that's not right? Some dry air in the mid-levels would be welcome.

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#1012629 - 17/09/2011 09:43 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
snowbaby Offline
Weather Freak

Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
The GFS is reputed to be a little trigger happy when it comes to moisture - I'm not sure haven't watched it that closely. I think BOM has upgraded their rainfall for Sunday a touch in last little while..

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#1012682 - 17/09/2011 14:50 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: snowbaby]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Quote:
SYNOPTIC SUMMARY:
A cold front is approaching the SW district. Isolated showers near west coastal
parts south of Perth, extending southwest of a line Jurien Bay to Walpole during
the afternoon and evening.
On Sunday the cold front is expected to reach the SW Capes early Sunday morning,
moving eastwards to lie near Lancelin to Albany about sunrise, Kalbarri to
Esperance early afternoon and slipping away into the Bight during the evening. A
period of scattered showers, gusty winds and isolated thunderstorms is expected
over central and southern districts with the passage of the front and moderate
to heavy falls are possible. Showers tending isolated with lighter falls over
northern districts. Strong and squally W/NW winds in the eastern parts.


GFS has also backed down on the moisture for the afternoon , morning soundings still look the same. Not sure if these storms will be a big event, unless a squall line develops ahead of the front.


Edited by Big_Pete (17/09/2011 14:53)
Edit Reason: Changed info.

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#1012712 - 17/09/2011 19:10 Re: Sth WA: Cold fronts and windy conditions 17th-23rd September 2011 [Re: Big_Pete]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
TOP PRIORITY FOR IMMEDIATE BROADCAST
SEVERE WEATHER WARNING

for Widespread Damaging Winds
For people in inland parts of WA in, near or between Kellerberrin to Paynes Find
to Sandstone to Leonora to Israelite Bay to Hopetoun to Kellerberrin. This
includes people in, near or between Southern Cross, Kalgoorlie, and Esperance.
Issued at 4:05 pm on Saturday 17 September 2011

A strong cold front expected near Lancelin to Albany about sunrise Sunday, Mount
Magnet to Esperance early Sunday afternoon, and Leinster to Israelite Bay late
afternoon. Showers and thunderstorms with the passage of the cold front are very
likely to produce WIDESPREAD DAMAGING WINDS to 100 kilometres per hour that
could cause DAMAGE TO HOMES AND PROPERTY. Damaging winds are likely to start
from late Sunday morning.

WHAT TO DO
For personal safety FESA State Emergency Service [SES] advises you to secure
loose objects, move vehicles under cover and stay inside away from windows. If
caught outside you should find shelter away from trees, powerlines, storm water
drains and streams. For SES assistance call 132 500. For more safety tips visit
www.fesa.wa.gov.au.


The next warning will be issued by 10:00 pm Saturday

This warning is also available through TV and Radio broadcasts; the Bureau's
website at www.bom.gov.au or call 1300 659 213.

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