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#1436834 - 12/10/2017 19:29 SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 6664
Loc: Maryborough, Wide Bay, QLD
During tomorrow a broad trough linked to a coastal change will move up the SE coast with showers and storms developing along and to its north. Obs and reports can go in the last day of the other thread for this.

Moving onto Saturday, we start to see the very beginnings of the development of what will become a very large upper trough over the southern half of QLD. This will be the main trigger for the enhanced rainfall from Sat-Mon. Meanwhile, the coastal change has virtually stalled somewhere on the Sunshine Coast, with showers and storms continuing initially to its north. During the day, this trough deepens quite rapidly due to the formation of the upper trough, and a deep onshore flow develops along and to the trough's south (positioning of coastal change is crucial as to where the heaviest rainfall will occur, as usual).

Onto Sunday, the upper trough has matured further and has developed a broad upper low center over SEQ. The original coastal trough appears to have moved inland over SEQ but still lags back over the coast of NE NSW. EC / GFS are in disagreement with how much rainfall will extend into NE NSW, with GFS being the most conservative of the two. Meanwhile a new trough forms north of Fraser Island with a deepening pressure gradient to its south, leading to strengthening winds along the SE Coast.

Onto Monday, the trough north of Fraser Island heads towards the Capricornia coast with heavy rain areas to its immediate south grading to showers into SEQ. At the same time, a very, very strong ridge develops over southern states which will eventually begin to clear everything away to the north.

Now for some charts, first is GFS accumulated rainfall to 4pm Tuesday, second is EC accumulated rainfall to 7pm Tuesday, third illustrates the two troughs, black dotted lines are the troughs, blue arrows indicate the tightening pressure gradient / stronger winds behind the CS trough. Fourth is a look at the upper trough - it's a doozie! Please also remember in setups like this, things can change in an instant so we won't really know where the heaviest of the rainfall will be probably until just before it happens.







Edited by Seabreeze (17/10/2017 18:22)
Edit Reason: extended by a day

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#1436835 - 12/10/2017 19:45 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
Mad Elf #1.5 Offline
Weatherzone Addict

Registered: 05/03/2012
Posts: 2963
Loc: Mt Hallen QLD
Thanks for the detailed explanation Mega, good job.


Edited by Mad Elf #1.5 (12/10/2017 19:45)

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#1436875 - 13/10/2017 00:49 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
CirrusFibratus Offline
Weather Freak

Registered: 17/09/2015
Posts: 313
Loc: Strathpine, QLD
Indeed, much appreciated. Bring on some more rain.
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#1436879 - 13/10/2017 06:47 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
paulcirrus Offline
Weatherzone Addict

Registered: 08/08/2011
Posts: 1468
Loc: Brisbane - Windsor
Nice Mega, well done


Edited by paulcirrus (13/10/2017 06:48)
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If it's Flooded - FORGET IT

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#1436884 - 13/10/2017 07:34 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
Blowin' Offline
Weather Freak

Registered: 23/08/2014
Posts: 863
Loc: Diamond Valley, Sunshine Coast
Fizzer...
Lol
Some impressive totals on gfs accumulated. Bsch has 480mm in Tin Can Bay.
Seems to be a slight southerly shift and intensification with each run. On high alert here.

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#1436900 - 13/10/2017 09:56 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
Locke Offline
Weatherzone Addict

Registered: 27/12/2007
Posts: 4368
Loc: Brisbane
Latest GFS has shifted South with the heaviest falls centred around the Brisbane CBD with over 300mm falling in 6 hours on Monday.

No doubt the target bullseye and rainfall totals will shift around in the coming 3 days but significant rainfall amounts will be experienced at some location on the SE QLD coast in the coming days.
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This post and any other post by Locke is NOT an official forecast & should not be used as such. It's just my opinion & may or may not be backed by sound meteorological data. For official information, refer to Australian Bureau of Meteorology products.

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#1436903 - 13/10/2017 10:03 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
petethemoskeet Offline
Weatherzone Addict

Registered: 13/08/2003
Posts: 1256
Loc: toowoomba
As long as it doesn't keep shifting further south and ends up in NE NSW.

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#1436905 - 13/10/2017 10:05 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
wet sky Offline
Weather Freak

Registered: 10/10/2015
Posts: 628
Loc: NENSW-Wet Subtropics
Yea Pete, GFS really moved the heavy rain south in the last run. Ken as usual on the money when he says its always better to be south of predicted rainfall. Brissy in on the bullseye atm (according to GFS), but 100mm+ totals extend down to Coffs on BSCH next 8 days forecast.

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#1436906 - 13/10/2017 10:10 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
Steve O Offline
Weatherzone Addict

Registered: 02/03/2011
Posts: 2956
Loc: Beenleigh, QLD
I noticed that models had a big ridge building up and pushed most of the activity north but intially starting south to begin. Looks like an ECL setup and that bullseye is going to change but be mainly looks to be somewhere coastal for that,though with the upper trough where it is should atleast help with some precip further inland.


Edited by Steve O (13/10/2017 10:12)

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#1436911 - 13/10/2017 10:42 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
Raweth Offline
Weather Freak

Registered: 02/02/2011
Posts: 357
Loc: Darling Heights, Toowoomba, QL...
I'm so bummed. We've been planning a beach trip to the Gold Coast for the past month for this weekend, for my birthday and I can't see any reason to bother driving two and a half hours or so to go now. frown

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#1436914 - 13/10/2017 10:56 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
petethemoskeet Offline
Weatherzone Addict

Registered: 13/08/2003
Posts: 1256
Loc: toowoomba
Raweth if the rain does eventuate because it's your birthday you can always get wet on the inside LOL

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#1436924 - 13/10/2017 12:25 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
Mad Elf #1.5 Offline
Weatherzone Addict

Registered: 05/03/2012
Posts: 2963
Loc: Mt Hallen QLD
That bullseye blob is very welcome to shift a bit to the left, right over our place!
Probably wont happen now that I requested it LOL.

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#1436929 - 13/10/2017 12:55 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
Locke Offline
Weatherzone Addict

Registered: 27/12/2007
Posts: 4368
Loc: Brisbane
To me the thing that is rarely picked up is the extremes that sometimes fall at certain points on the ranges.

Like the 4-500mm plus totals you sometimes see at places like Mt Glorious or Springbrook.

Whenever I see 200-300mm totals forecast for short time frames there's always in the back of my mind the possibility of more extreme totals in those locations I mentioned.
_________________________
This post and any other post by Locke is NOT an official forecast & should not be used as such. It's just my opinion & may or may not be backed by sound meteorological data. For official information, refer to Australian Bureau of Meteorology products.

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#1436930 - 13/10/2017 12:59 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Locke]
Blowin' Offline
Weather Freak

Registered: 23/08/2014
Posts: 863
Loc: Diamond Valley, Sunshine Coast
Absolutely, and this is the dangerous times for crossing flooded roads downstream.
Iím surprised we havenít heard Inclement Weathers view on this setup. I suspect he may be sandbagging!


Originally Posted By: Locke
To me the thing that is rarely picked up is the extremes that sometimes fall at certain points on the ranges.

Like the 4-500mm plus totals you sometimes see at places like Mt Glorious or Springbrook.

Whenever I see 200-300mm totals forecast for short time frames there's always in the back of my mind the possibility of more extreme totals in those locations I mentioned.

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#1436931 - 13/10/2017 13:14 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: petethemoskeet]
Raweth Offline
Weather Freak

Registered: 02/02/2011
Posts: 357
Loc: Darling Heights, Toowoomba, QL...
Thanks. smile We might not get much in our neck of the woods, I'm assuming. Hope you have a good weekend whatever you may be up to.

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#1436939 - 13/10/2017 14:51 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Blowin']
Locke Offline
Weatherzone Addict

Registered: 27/12/2007
Posts: 4368
Loc: Brisbane
Originally Posted By: Blowin'
Absolutely, and this is the dangerous times for crossing flooded roads downstream.
Iím surprised we havenít heard Inclement Weathers view on this setup. I suspect he may be sandbagging!


Originally Posted By: Locke
To me the thing that is rarely picked up is the extremes that sometimes fall at certain points on the ranges.

Like the 4-500mm plus totals you sometimes see at places like Mt Glorious or Springbrook.

Whenever I see 200-300mm totals forecast for short time frames there's always in the back of my mind the possibility of more extreme totals in those locations I mentioned.


Agree 100%.

Its the one thing that saddens me when I see setups like this with forecast rainfall rates in the 50-100mm/h range. The knowledge that if they prove accurate there's a very good chance that someone will perish whilst driving in floodwaters.
_________________________
This post and any other post by Locke is NOT an official forecast & should not be used as such. It's just my opinion & may or may not be backed by sound meteorological data. For official information, refer to Australian Bureau of Meteorology products.

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#1436950 - 13/10/2017 15:43 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 6664
Loc: Maryborough, Wide Bay, QLD
00z GFS holding from its 18z run, but 00z ACCESS-R & CMC look nothing like that come Monday.

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#1436954 - 13/10/2017 16:04 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
Nature's Fury Offline
Weatherzone Addict

Registered: 29/11/2009
Posts: 1917
Loc: Brisbane Western Suburbs
I have this terrible sinking feeling that we're going to see all the main falls offshore or shift down into NSW. Access-R is already trending this way.

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#1436959 - 13/10/2017 16:28 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: Mega]
grayarea Offline
Weather Freak

Registered: 12/05/2007
Posts: 524
Loc: Doonan, Sunshine Coast
Gympie on 43mm already

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#1436970 - 13/10/2017 19:41 Re: SEQLD/NENSW - Rain Event, possible heavy falls 14th-17th October 2017 [Re: grayarea]
Nature's Fury Offline
Weatherzone Addict

Registered: 29/11/2009
Posts: 1917
Loc: Brisbane Western Suburbs
EC shifting focus to NE NSW.

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