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#1435449 - 29/09/2017 10:41 SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017
Ken Kato Offline
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Registered: 05/03/2012
Posts: 4683
The end date of this thread is fairly open-ended so it could change by then... but thought I'd get this started anyway. As usual, I'm not going to get excited til around the day or two before.

A deepening surface trough and positively tilted upper trough combined with a moist onshore flow should cause enhanced rainfall to develop around the southeastern quarter of QLD and northeast NSW by early to mid next week. Some models also suggest a very small low may eventually develop near the southern QLD coast but that's still up in the air.

I'll leave all the finer details and discussion up to others for now since I'm in a rush but below are some graphics (the probabilities of greater than 25mm one is technically the percentages of the 62 forecast scenarios from a few of the ensembles dropping more than 25mm of accumulated rainfall during next week):






Edited by Seabreeze (03/10/2017 23:02)
Edit Reason: gave a definitive end date

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#1435456 - 29/09/2017 11:08 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
Mad Elf #1.5 Offline
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Registered: 05/03/2012
Posts: 2904
Loc: Mt Hallen QLD
Thanks for those charts Ken, I'll hold off carting water until next week. WATL has also been consistent last few days, so I leave it at that & not jinx the bloody thing!
Heating up well atm, 35.5C 18%RH & calm.


Edited by Mad Elf #1.5 (29/09/2017 11:12)

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#1435458 - 29/09/2017 11:21 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
grayarea Offline
Weather Freak

Registered: 12/05/2007
Posts: 523
Loc: Doonan, Sunshine Coast
Well hoping for some rainfall also to avoid purchasing water.

I don't understand why BOM forecasts are so stand offish when other models EC, GFS, OCF are all going for more than just occasional showers. Maybe they too don't want to jinx anything.

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#1435463 - 29/09/2017 12:02 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
Blowin' Offline
Weather Freak

Registered: 23/08/2014
Posts: 854
Loc: Diamond Valley, Sunshine Coast
Thanks Ken,

Look out northern nsw!

isn't the theme to date that the forcast a 5-7 days out has wide bay/sunny coast copping a drenching but the low ends up forming south of the border and they get 200mm while we get 4mm with the passage of the trough and light south westerlies up here? Haha

Definitely a southward trend in the models - it was Hervey Bay a few days ago...

I'll wash the car and pre-pay for a water delivery, that might help...

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#1435481 - 29/09/2017 14:59 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
PlumbBob Offline
Weather Freak

Registered: 07/05/2011
Posts: 512
Loc: Ashmore Gold Coast
Layman post from this duck, but still, ;-)
Seen a hint of this the other day, and just now viewed the typical Synoptic, lets hope for anything, very dry here on the GC, even the biggest of gum trees have wilted !

Good thing the Major Dams are still very healthy, tho, the way things are going, one's mind can wander back a decade or two ago to that 6-7yr drought where occasionally good rain came, but never hit the catchments ? ?

Flat-out received 0.2mm from the stormage last week - the concrete around here is greener than the grass atm, was thinking about mowing the carport, just to turn the mower over, Lol ;-)
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#1435482 - 29/09/2017 15:13 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
Inclement Weather Offline
Meteorological Motor Mouth

Registered: 07/03/2006
Posts: 5187
Loc: Diamond Valley
Thanks for starting the thread Ken. Goodness knows we need the rain desperately. I've never seen so many water tankers in our neck of the woods. Certainly the cards are falling (if nor the rain yet) for this potential event. Classic trifecta of a deepening surface trough, enhanced by an upper trough, and fed by moist easterlies always plays well for SEQ.
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#1435490 - 29/09/2017 16:37 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
Mad Elf #1.5 Offline
Weatherzone Addict

Registered: 05/03/2012
Posts: 2904
Loc: Mt Hallen QLD
BOM official forecasts now agree with models. Gona get something!

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#1435511 - 29/09/2017 21:49 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 6623
Loc: Maryborough, Wide Bay, QLD
Just some fleeting thoughts....

GFS clearly an outlier, while most models I've seen focus the heaviest falls in the north of SEQ, GFS just drenches the entire coast as the inland low/trough dips a lot further south than the others. Two things:

1. The upper low is much stronger on GFS
2. GFS fails to build the ridge in under trough/low, hence the entire trough/low slips SSE and pops off the NE NSW rather than anchoring further north. Some charts to show my reasoning:

GFS:


-Blue arrows represent the anti-clockwise rotation around the two upper level ridges. Note the position of the 'H' over SA - this is the ridge that doesn't build in as quickly as EC nor the rest.
-Green arrow represents the broad inland trough
-Black arrow represents the gap or 'weakness' between the two ridges or 'H's. Hence the low is able to slip further south, between the two.

2. EC:


-Again the blue lines represent the ridge. As you can see, the main center of the western ridge is over Victoria, whereas GFS was still over SA. The two (Vic & Tasman Sea 'H') look to have pretty well merged here
-Green arrow represents the deep inland trough or broad low - but it's anchored further north because there's no weakness in the ridge as seen in the GFS example.

Final thoughts: GFS solution would give everybody from southern CQ right through to NE NSW a solid drink as the trough slips SSE and a new low pops off the coast mid-week. EC solution would likely hold the heaviest rainfall in SEQ or even further north, ACCESS-G just out actually has the heaviest falls remaining north of Brisbane but it's probably being a little conservative for SEQ on the precip side of things considering we'll be under the influence of a very moist E/NE air flow.

Isn't it good to finally have some weather to talk about...

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#1435531 - 30/09/2017 10:06 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
Ken Kato Offline
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Registered: 05/03/2012
Posts: 4683
Great analysis Mega smile

There's still some uncertainty about the positioning, movement and amplitude of the upper troughs as well as the evolution of the surface features... and therefore, uncertainty about the positioning of the heavier rainfall.

A number of models currently have the heavier rainfall to our north and west, while a smaller proportion spread the heavier stuff over us.

As Blowin' mentioned, I always prefer to be a bit "too" far south than too far north when it comes to most systems but I just hope this system doesn't stay TOO far north.

If we happen to get into the sweet spot of max upmotion around 1/3rd to 1/2 of the wavelength downstream of the upper troughs, it'll be good.

Here's some graphics below (that unusually wide spread of rainfall scenarios is mainly due to the uncertainty with the positioning of the upper troughs and surface features):





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#1435532 - 30/09/2017 10:09 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
Timbuck Offline
Weather Freak

Registered: 08/10/2013
Posts: 191
Loc: Highland park , Gold Coast
Thanks for starting the thread.


Where is everyone smile smile smile. I thought after months of talking about dry ground , burn grass , no feed , empty tanks this thread would be blooming with spring exitment smile smile smile
Great to see a nice set up that a large area will get some of the wet stuff. As others have said , this is the tide turning hopefully smile

I was ment to be taking nice and nephews on there first camping trip tomorrow for the week up to girraween NP.
Now flipping a coin where to go and excape into some more camping friendly area. Might head south and go to mt kaputar NP , hopefully will be at the egde of the main rain if the system slides SSE.
Kids love fossicing and bush walking so we have the best of both worlds down there.


Hope everone get a drink out of this one.

Cheers

Tim

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#1435533 - 30/09/2017 10:16 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
NotsohopefulPete Offline
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Registered: 24/12/2008
Posts: 1087
Loc: Toowoomba
Maybe some of us are just too afraid to believe it may actually happen to comment.


Edited by Hopefull (30/09/2017 10:16)

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#1435535 - 30/09/2017 10:25 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: NotsohopefulPete]
Timbuck Offline
Weather Freak

Registered: 08/10/2013
Posts: 191
Loc: Highland park , Gold Coast
Haha. Yes agreed. At least your up the mountain now , so you should be right amongst it. Won't be long and you will have to mow the lawn , let's hope everyone has too smile


I did like that even spread of rain scenario's on that graph. More than a each way bet that's for sure.


Edited by Timbuck (30/09/2017 10:27)

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#1435536 - 30/09/2017 10:31 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
NotsohopefulPete Offline
Weatherzone Addict

Registered: 24/12/2008
Posts: 1087
Loc: Toowoomba
Mowing the lawn? yes, I do vaguely remember that chore. But today is the same never-ending westerly. It will great to see the end of it.


Edited by Hopefull (30/09/2017 10:33)

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#1435540 - 30/09/2017 10:53 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
Mad Elf #1.5 Offline
Weatherzone Addict

Registered: 05/03/2012
Posts: 2904
Loc: Mt Hallen QLD
Thats a good size area on WATL thats gona get quite a drink. Cant wait, getting excited just looking at that high cloud strraming in from the west.


Edited by Mad Elf #1.5 (30/09/2017 10:53)

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#1435546 - 30/09/2017 11:26 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
ozone doug Offline
Weatherzone Addict

Registered: 06/11/2006
Posts: 1663
Loc: Roma SW QLD Eye to the West...
Whoo whoo lol ,Looking forward to tomorrow .Up to 40mm forecast for here.
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#1435547 - 30/09/2017 11:27 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
Inclement Weather Offline
Meteorological Motor Mouth

Registered: 07/03/2006
Posts: 5187
Loc: Diamond Valley
Is anyone else experiencing problems with the BSCH site or the Meteostar site?
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#1435549 - 30/09/2017 11:33 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Inclement Weather]
CirrusFibratus Offline
Weather Freak

Registered: 17/09/2015
Posts: 299
Loc: Strathpine, QLD
Originally Posted By: Inclement Weather
Is anyone else experiencing problems with the BSCH site or the Meteostar site?

Not just you Inclement, I'm getting a 502 error on their site.
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#1435551 - 30/09/2017 11:41 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: CirrusFibratus]
Colin Maitland Offline
Weatherzone Addict

Registered: 01/09/2009
Posts: 2383
Loc: North Brisbane ( Bracken Ridge...
Originally Posted By: CirrusFibratus
Originally Posted By: Inclement Weather
Is anyone else experiencing problems with the BSCH site or the Meteostar site?

Not just you Inclement, I'm getting a 502 error on their site.


Totally agree, must just be you Inclement, unlike CirrusFibratus with a 502 I am getting a very clear and nice bigger number of 522 error, it also has pictures telling me I may have done something wrong. evillaugh

No it is down IW. Probably the solar storm from last week has caught up with us. X9.3 and X8.2 are pretty big solar flares.
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#1435552 - 30/09/2017 11:59 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Ken Kato]
Inclement Weather Offline
Meteorological Motor Mouth

Registered: 07/03/2006
Posts: 5187
Loc: Diamond Valley
Okay, thanks guys - glad to know it's not just me.
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#1435554 - 30/09/2017 12:02 Re: SE QLD/NE NSW - Enhanced rainfall - 1st to 4th Oct 2017 [Re: Inclement Weather]
Nature's Fury Offline
Weatherzone Addict

Registered: 29/11/2009
Posts: 1878
Loc: Brisbane Western Suburbs
Now all we need is for Stapylton to go down and the failure is complete.

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