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#1473491 - 14/10/2018 12:03 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
Blowin' Offline
Weatherzone Addict

Registered: 23/08/2014
Posts: 1009
Loc: Diamond Valley, Sunshine Coast
Low centred near eurong?

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#1473493 - 14/10/2018 12:10 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
gleno71 Offline
Weatherzone Addict

Registered: 09/11/2007
Posts: 1868
Loc: Australia
Rain eased a bit on the Gold Coast, though still heavy on the hinterland.

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#1473497 - 14/10/2018 12:57 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
one drop Offline
Weather Freak

Registered: 15/04/2014
Posts: 117
Loc: maryborough
imo bom were a bit quick to cancel the flood watch and head home for saturday afternoon drinks. crazy

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#1473499 - 14/10/2018 13:08 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 7899
Loc: Maryborough, Wide Bay, QLD
You know it's hard to identify a singular circulation when even BoM revert back to saying "low pressure complex" instead of "low pressure system".

Anyway, I'm really surprised by this rain today as most if not all models had the heavier stuff much further south by now. I also noticed models had very heavy falls already occurring from the Sunshine Coast south from early this morning which still isn't occurring (yes, there's plenty of showers down there but not huge falls yet as some models were predicting). Convergence does look to be heading south though so the stuff to watch is probably off the northern SC right now.

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#1473500 - 14/10/2018 13:10 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
GFS suggests low pressure just east of Maroochydore, 500hp low just west of Brisbane, and 300hp upper level trough NE/SW through Bundaberg. Gympie doppler wind hints at a low a little further north than GFS suggests, maybe east of Rainbow Beach. GFS suggests the low is pretty stretched towards the north, almost a trough so could be why.

Steering winds should push low towards south, but high pressure trap it, and with strength and position towards NZ no surprise it might push the low pressure towards the coast.

Enhanced rainfall to the north of SS coast is a concern for SS coast which is very saturated, with the hint that the rainfall might be further north than forecast, but I think its due to the upper level features and not a secondary low pressure or the main one being further north. Forecasts don't expect enough rain to be a flooding risk and flood watch has been cancelled, but definitely one to watch just in case.


Edited by Mike Hauber (14/10/2018 13:12)

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#1473501 - 14/10/2018 13:17 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
Ken Kato Offline
Meteorological Motor Mouth

Registered: 05/03/2012
Posts: 6090
Yep Mega, every time there's potential for multiple low pressure centres embedded in a broader area of low pressure or trough, it raises red flags for me in terms of uncertainty in movement and intensities.

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#1473502 - 14/10/2018 13:23 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Mike Hauber]
Ken Kato Offline
Meteorological Motor Mouth

Registered: 05/03/2012
Posts: 6090
Originally Posted By: Mike Hauber
GFS suggests low pressure just east of Maroochydore, 500hp low just west of Brisbane, and 300hp upper level trough NE/SW through Bundaberg. Gympie doppler wind hints at a low a little further north than GFS suggests, maybe east of Rainbow Beach. GFS suggests the low is pretty stretched towards the north, almost a trough so could be why.

Steering winds should push low towards south, but high pressure trap it, and with strength and position towards NZ no surprise it might push the low pressure towards the coast.

Enhanced rainfall to the north of SS coast is a concern for SS coast which is very saturated, with the hint that the rainfall might be further north than forecast, but I think its due to the upper level features and not a secondary low pressure or the main one being further north. Forecasts don't expect enough rain to be a flooding risk and flood watch has been cancelled, but definitely one to watch just in case.


Yeah, the models indicate the surface troughing is tilting to the north with height with a more distinct troughing (even arguably a low) in the midlevels.

I'm not putting too much faith in GFS atm though - once again, even though many models have moved the surface feature south too fast (so far at least anyway), GFS was even further off the mark than many of the others (yesterday's 00z run had it a fair way out to sea east of SE QLD by now). It's hard to know for sure which models are going to be closer to the mark for any given individual setup but the fact that objective skill scores consistently show that GFS is significantly less accurate than some of the other models is hard to ignore. Hopefully its successor will be better in our part of the world. I find it often does do fairly well with TC tracks as well as CAPE fields though. In the meantime, always good to look at all of them to get an idea of the spread of potential scenarios and do a blended consensus approach.

P.S. latest 00z ACCESS-C is out and now tries to ramp up the precip along the coast this afternoon before focussing heavier rainfall over the far southeast corner of SE QLD into this evening.


Edited by Ken Kato (14/10/2018 13:31)
Edit Reason: added stuff

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#1473504 - 14/10/2018 13:35 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
DDstorm Offline
Weather Freak

Registered: 13/05/2010
Posts: 388
Loc: Tallai, QLD
Quite a large blob headin in on the goldy from the east on 256k.
Been plenty of heavy showers here this morning.
DD
_________________________
Just here for the weather

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#1473505 - 14/10/2018 13:37 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
Namarrkun Offline
Weather Freak

Registered: 17/11/2012
Posts: 571
Loc: Salisbury
Hoping to crack the 50.0mm event total mark at some stage today, currently sitting on 49.8mm

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#1473507 - 14/10/2018 13:48 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
Blowin' Offline
Weatherzone Addict

Registered: 23/08/2014
Posts: 1009
Loc: Diamond Valley, Sunshine Coast
Love both th novice and experienced commenty on this forum- thank you!
I just look for a central point in rotation on the radar , but understand itís a lot more complex than that.
Definitely looks like a wet arvo/night inbound from the east

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#1473508 - 14/10/2018 13:50 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
Mad Elf #1.5 Offline
Weatherzone Addict

Registered: 05/03/2012
Posts: 3859
Loc: Mt Hallen QLD
Frequent heavy drizzle/showers here now & darker. Love all this incoming moisture!

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#1473509 - 14/10/2018 13:56 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Ken Kato]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
Originally Posted By: Ken Kato
[

It's hard to know for sure which models are going to be closer to the mark for any given individual setup but the fact that objective skill scores consistently show that GFS is significantly less accurate than some of the other models is hard to ignore.


How does it compare to Access? I have the impression from somewhere it is overall significantly ahead of Access and close to EC, which leads. Maybe thats old stuff based on pre-Access performance (NOGAPs or whatever it was called). But GFS data is so much more accessible than EC eg BSCH stormcast. So I use a lot of GFS and check against what is available on Tropical Tidbits for EC. Maybe I need to go premium Weatherzone or something to get better EC access.


Edited by Mike Hauber (14/10/2018 14:03)

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#1473513 - 14/10/2018 14:06 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
gleno71 Offline
Weatherzone Addict

Registered: 09/11/2007
Posts: 1868
Loc: Australia
I'm at Point Danger and its howling. Someone got knocked over by the wind near the monument. There ok. Big band heading towards the GC. Surf is messy but huge waves. Some light erosion st Duranbah beach

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#1473514 - 14/10/2018 14:06 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Mike Hauber]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 7899
Loc: Maryborough, Wide Bay, QLD
Originally Posted By: Mike Hauber
Originally Posted By: Ken Kato
[

It's hard to know for sure which models are going to be closer to the mark for any given individual setup but the fact that objective skill scores consistently show that GFS is significantly less accurate than some of the other models is hard to ignore.


How does it compare to Access? I have the impression from somewhere it is overall significantly ahead of Access and close to EC, which leads. Maybe thats old stuff based on pre-Access performance (NOGAPs or whatever it was called).


Ah, good old LAPS, MLAPS and GASP...those were the days.

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#1473515 - 14/10/2018 14:06 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Mike Hauber]
Ken Kato Offline
Meteorological Motor Mouth

Registered: 05/03/2012
Posts: 6090
Originally Posted By: Mike Hauber
Originally Posted By: Ken Kato
[

It's hard to know for sure which models are going to be closer to the mark for any given individual setup but the fact that objective skill scores consistently show that GFS is significantly less accurate than some of the other models is hard to ignore.


How does it compare to Access? I have the impression from somewhere it is overall significantly ahead of Access and close to EC, which leads. Maybe thats old stuff based on pre-Access performance (NOGAPs or whatever it was called). But GFS data is so much more accessible eg BSCH stormcast. So I use a lot of GFS and check against what is available on Tropical Tidbits for EC.


On average, GFS skill in most parameters is less than ACCESS-G and much less than EC and UK.

But the most important thing to remember is that that's on average. Sometimes, GFS is closer to the mark than EC, etc and often it's not. It's only when you look at the skill for a large sample size that it becomes more obvious. So for any given setup, it still shouldn't be completely ignored - rather, it should be viewed as one of the available models, how it fits in with the consensus of other models, how it's handling a particular situation, etc.
In other words, a single model shouldn't be the only model relied on, even if it's EC.

Here's a graph showing the 24hr precip skill scores over the AU/NZ region as a function of forecast lead time of some of the global models compared with each other. The score technique takes into account the distribution and nature of the rainfall e.g. patchy drizzle vs convective showers/storms vs widespread rain, etc. These scores are averaged over a 3 month period centred on the most recent August we had. The rankings of those models don't change that much. EC/UK are usually no.1 and 2 respectively while GFS (green) is usually 3rd or 4th:



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#1473516 - 14/10/2018 14:12 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
A bit surprising to me that UK/BOM are ahead of GFS. I think my perception is coloured by ENSO performance where BOM/UK seem to be pretty poor and CFS not fare from EC. Some objective stats I managed to track down from about 2012 showed that quite clearly, and what I've seen since hasn't seemed to change that greatly.

GFS is still mighty impressive compared to what forecasting was like in the 90s though lol.

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#1473517 - 14/10/2018 14:17 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
Ken Kato Offline
Meteorological Motor Mouth

Registered: 05/03/2012
Posts: 6090
The seasonal forecast versions of the models often use schemes with a lot of differences (quite aside from the fact that seasonal forecasts are ensemble versions of each model) from their medium range versions so it's tricky to compare the two.

I haven't checked that recently but I do remember EC had better skill with seasonal forecasts than a number of other models and POAMA (the seasonal forecast model that the Bureau used but now transitioning to ACCESS-S) had better skill than many others as well. May or may not have changed since I last checked.

But yeah, forecasting's come a long way since the old days. And not just technology but also our knowledge of the mechanisms with various phenomena and weather systems which helps a lot as well.


Edited by Ken Kato (14/10/2018 14:18)

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#1473521 - 14/10/2018 15:24 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
one drop Offline
Weather Freak

Registered: 15/04/2014
Posts: 117
Loc: maryborough
looks a little more like a low now, on radar, centred around a point east of about poona maybe?


Edited by one drop (14/10/2018 15:24)

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#1473523 - 14/10/2018 15:33 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: Seabreeze]
Blowin' Offline
Weatherzone Addict

Registered: 23/08/2014
Posts: 1009
Loc: Diamond Valley, Sunshine Coast
Yeah Poona- eurong east and down to rainbow beach I recon. Hasnít moved much today.

Could also elongate further southeast as the trough/multi centred low that was mentioned.

Just my interpretation but thatís just of the radar

Higgins is posting warnings... northern SC to the border

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#1473524 - 14/10/2018 15:33 Re: SEQLD/NENSW Rain & Thunderstorms (including the Tansey Tornado) - 4th to 16th October 2018 [Re: one drop]
Nature's Fury Offline
Weatherzone Addict

Registered: 29/11/2009
Posts: 2545
Loc: Brisbane Western Suburbs
That big band coming in off GC should swing up and into SEQ. Some good falls coming.

Also, Ken thanks for your illuminating analysis of the modelling. Where does Access-R fit in? It is only useful for short-term convective rain/storms (although it is terrible for night-time or day-to-night transitional rain) or can it be useful for broader scale events like this one. It seems to have done pretty well so far, much better than GFS.


Edited by Nature's Fury (14/10/2018 15:34)

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