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#1479528 - 12/12/2018 10:14 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: TWEEDSTORM]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 966
Loc: Pinjarra Hills, Qld
Originally Posted By: TWEEDSTORM
Originally Posted By: Nature's Fury
EC is still the only model going past Fraser. And GFS is the only one that keeps it relatively strong up to Fraser. All the rest keep it further north and weaker. My money is on EC backing down as soon as this evening.


Think ya right NF that low has to compete with a brick wall of a strengthening ridge looking at latest Access maps.


Models will probably tease us more for a while yet. The 18Z GFS now has the southern extent closer to the latitude of the NSW/QLD border. I am keen to see the GFS-FV3 -- 18Z result not yet fully available.


Edited by Flowin (12/12/2018 10:15)
Edit Reason: tidy up
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#1479531 - 12/12/2018 10:27 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Nature's Fury]
Ken Kato Offline
Meteorological Motor Mouth

Registered: 05/03/2012
Posts: 6090
Letís not forget that on average, a middle of the ground consensus track using all models (combined with knowledge & experience of TC principles, past similar cases and some previous but recent runs) is more skilful than just relying on a single one, even if it is the most accurate model like EC.

This sometimes wonít be the case and the observed track can occasionally coincide with a single model or even lie just outside the spread of all models but it happens often enough to statistically be the most accurate method on average (and which is why itís the main basis for official track forecasts beyond the immediate timeframe for weather agencies around the world).

Itís easy and tempting to get fixated too much on one particular model even if it is EC no matter how good it is. Time will tell if it does happen to go exactly ECís way but for now, a consensus approach is a good way to go.

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#1479533 - 12/12/2018 10:30 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Nature's Fury]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
Some(many) catchments may be bone dry, but the Sunshine Coast catchments aren't. Soil in my backyard was getting reasonably saturated again a few days ago with the recent shower activity, although the surface has been drying out quickly again last few days.

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#1479535 - 12/12/2018 10:35 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Mike Hauber]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 966
Loc: Pinjarra Hills, Qld
Originally Posted By: Mike Hauber
Some(many) catchments may be bone dry, but the Sunshine Coast catchments aren't. Soil in my backyard was getting reasonably saturated again a few days ago with the recent shower activity, although the surface has been drying out quickly again last few days.

Agree the north coast not as dry as south and west parts of SEQ
http://www.bom.gov.au/water/landscape/#/sm/Relative/day/-25.67/151.83/6/Point////2018/12/11/

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#1479536 - 12/12/2018 10:38 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Ken Kato]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 966
Loc: Pinjarra Hills, Qld
Originally Posted By: Ken Kato
Letís not forget that on average, a middle of the ground consensus track using all models (combined with knowledge & experience of TC principles, past similar cases and some previous but recent runs) is more skilful than just relying on a single one, even if it is the most accurate model like EC.

This sometimes wonít be the case and the observed track can occasionally coincide with a single model or even lie just outside the spread of all models but it happens often enough to statistically be the most accurate method on average (and which is why itís the main basis for official track forecasts beyond the immediate timeframe for weather agencies around the world).

Itís easy and tempting to get fixated too much on one particular model even if it is EC no matter how good it is. Time will tell if it does happen to go exactly ECís way but for now, a consensus approach is a good way to go.


Agree Ken. But also for a change in consensus to occur one or a few models change, then others change until enough align for the consensus to change. So still some interest in what the individual model trends are doing.
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#1479538 - 12/12/2018 10:43 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Flowin]
Ken Kato Offline
Meteorological Motor Mouth

Registered: 05/03/2012
Posts: 6090
Originally Posted By: Flowin
Originally Posted By: Ken Kato
Letís not forget that on average, a middle of the ground consensus track using all models (combined with knowledge & experience of TC principles, past similar cases and some previous but recent runs) is more skilful than just relying on a single one, even if it is the most accurate model like EC.

This sometimes wonít be the case and the observed track can occasionally coincide with a single model or even lie just outside the spread of all models but it happens often enough to statistically be the most accurate method on average (and which is why itís the main basis for official track forecasts beyond the immediate timeframe for weather agencies around the world).

Itís easy and tempting to get fixated too much on one particular model even if it is EC no matter how good it is. Time will tell if it does happen to go exactly ECís way but for now, a consensus approach is a good way to go.


Agree Ken. But also for a change in consensus to occur one or a few models change, then others change until enough align for the consensus to change. So still some interest in what the individual model trends are doing.

Yep for sure... however in the majority of cases, the multimodel consensus track tends to be more stable over consecutive runs than the individual models it consists of so it often takes a significant proportion or large shift of these individual models to cause a major change in the consensus track.

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#1479540 - 12/12/2018 10:47 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Nature's Fury]
Mezo Offline
Weather Freak

Registered: 01/12/2011
Posts: 742
Loc: Under the Meso (or Springfield...
Originally Posted By: Flowin
Originally Posted By: Chris Stumer
It would be interesting to know what the history is regarding ex-TCs in SEQ.

Others have commented on some. The complete list last two decades
In last 6 years
Debbie March 17
Marcia February 15
Oswald January 13
In 12 years 2000-2012 nil


We moved up here in 2012, so one of these events every couple of years just feels like the norm to me haha.
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#1479541 - 12/12/2018 10:57 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Nature's Fury]
Chris Stumer Offline
Weatherzone Addict

Registered: 28/01/2010
Posts: 1883
Loc: Kingaroy
I would think a ridge would push the system back further west and/or slow the system down a fraction.

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#1479542 - 12/12/2018 11:01 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Ken Kato]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 966
Loc: Pinjarra Hills, Qld
Originally Posted By: Ken Kato

Yep for sure... however in the majority of cases, the multimodel consensus track tends to be more stable over consecutive runs than the individual models it consists of so it often takes a significant proportion or large shift of these individual models to cause a major change in the consensus track.

Yes agree with that... At present I am interested not so much in the forecast outcome (still too early), but rather the forecast evolution. Some models have changed from the continuing southern track for several runs now, some models not even close to SEQ, and EC now one run with a change in direction away from the south pole graveyard ... so yes we need to wait and see.
That said I am fully aware that the lead time is still 5 days or so. Ken before has posted many charts of model skill being less at longer lead times. I can't recall many situations where we have seen this sort of consensus (over the last two days say) with more than 3 days lead time.
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#1479547 - 12/12/2018 11:30 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Coxy]
whynot Offline
Weather Freak

Registered: 01/10/2001
Posts: 550
Loc: Brisbane
Originally Posted By: Coxy


With our catchments being so bone dry, if we get sudden, persistent heavy rain is it more likely to run off than soak in? Curious about the science there.


If you dig through the archives in this Forum (SEQ/NEN), there is a lot of information about saturation rates and run offs for Brisbane catchments (with formulas and even a spreadsheet or two). Hard to believe that discussion was over a decade ago... time flies ...

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#1479549 - 12/12/2018 11:31 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Flowin]
wetdreams Offline
Weather Freak

Registered: 25/10/2010
Posts: 111
Loc: Mooloolah Valley QLD
Originally Posted By: Flowin
Originally Posted By: Mike Hauber
Some(many) catchments may be bone dry, but the Sunshine Coast catchments aren't. Soil in my backyard was getting reasonably saturated again a few days ago with the recent shower activity, although the surface has been drying out quickly again last few days.

Agree the north coast not as dry as south and west parts of SEQ
http://www.bom.gov.au/water/landscape/#/sm/Relative/day/-25.67/151.83/6/Point////2018/12/11/


Yes despite all of those BOM 'fails' over the last week or so, we've picked up falls between 4 and 10mm almost every day for the last 6 or 7 days. So while the ground is not saturated, it is far from dry.
Any shower activity in the days leading up to the main event will get us fully primed I'd expect.




Oh, and this is event is almost a sure thing now.
I've just got the call from the boss. He wants me in Sydney from this Saturday until Wednesday afternoon.
It's guaranteed major event on the Sunny Coast now... cry


Edited by wetdreams (12/12/2018 11:32)
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#1479553 - 12/12/2018 11:47 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Nature's Fury]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
So GFS and EC are somewhat close together now on a path directly into SEQ, with a stall just off the coast, probably far enough to avoid a worst case flooding scenario. Access doesn't want to back down though and has the system washing out even further north in the tropics. Difference seems to be Access doesn't want to intensify the system in the gulf as EC and GFS does so no staying power over land, and it looks quite likely that the system will intensify much more than Access has allowed for.

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#1479596 - 12/12/2018 16:16 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Nature's Fury]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 966
Loc: Pinjarra Hills, Qld
I am expecting that until Owen's landfall time, location, and strength is better understood in the next day or so as it exits the GOC waters onto land, the models may continue to change quite a bit in relation to the potential forecast track beyond that and whether it will get near SEQ.

Nonetheless this event thread is also about the potential storms around Friday from the southern cutoff low, and I am looking forward to that, as I have had enough of the dust, brown grass and we could all do with a drop of rain.
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Models are for estimating and gauges are for knowledge.

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#1479602 - 12/12/2018 16:48 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Nature's Fury]
Steve O Offline
Weatherzone Addict

Registered: 02/03/2011
Posts: 3494
Loc: Beenleigh, QLD
There may even be abit of convergence set up along the coast prior to the main event. Perhaps maybe another surface low could form in the convergence.

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#1479604 - 12/12/2018 16:52 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Nature's Fury]
Gringo2412 Offline
Cloud Gazer

Registered: 10/10/2018
Posts: 10
Hi everyone, long time reader here. I'm fairly new to these shores (pom now been here for 6 years). This forum, and particularly Ken's contributions have fascinated me for a while now.

I'm heading off to Perigian for a beach holiday tomorrow, perfect timing as always!

Hopefully everyone will get a good drink out of this.

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#1479606 - 12/12/2018 17:18 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Seabreeze]
Steven Offline
Weatherzone Addict

Registered: 19/04/2006
Posts: 2191
Loc: 中国上૲...
Getting in this post before the media go into a frenzy

Current dam levels for Wivenhoe (Brisbane):
At 7am Wed 2018/12/12 the level was at 62.83m AHD
This is 4.17m BELOW the 100% water storage compartment limit)

(As a comparision for 2011 - the level at Wivenhoe exceeded 74m AHD. The dam would have to rise over 11m to have a flood like 2011)

Brisbane R at Wivenhoe Dam 7.00am Wed 62.83 rising slowly

Summary: There is 0% chance of Brisbane having a major flood warning next week

GFS weather modelling is projecting heavy rainfall mostly confined to the coastline areas and offshore islands. Further inland should get reasonable rainfall but nothing exceptional.

I am more interested in the wind/seas forecast. Monday could be a very interesting day


Edited by Steven (12/12/2018 17:21)

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#1479616 - 12/12/2018 18:02 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Nature's Fury]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 7899
Loc: Maryborough, Wide Bay, QLD
EC only takes Owen down to about Gladstone now by the look of it. There were a few models hinting at this last night iirc.

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#1479618 - 12/12/2018 18:07 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Nature's Fury]
Steve O Offline
Weatherzone Addict

Registered: 02/03/2011
Posts: 3494
Loc: Beenleigh, QLD
Its forecast to move so quickly how does it just stop like that. Classic GFS moves south EC north lol. Welcome Gringo.


Edited by Steve O (12/12/2018 18:07)

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#1479619 - 12/12/2018 18:08 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Mega]
Nature's Fury Offline
Weatherzone Addict

Registered: 29/11/2009
Posts: 2545
Loc: Brisbane Western Suburbs
Originally Posted By: Mega
EC only takes Owen down to about Gladstone now by the look of it.


That's a big change in 1 run. And just when there was some nice model agreement with GFS.

Had a feeling it would change on this evening's run.

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#1479620 - 12/12/2018 18:08 Re: SEQLD/NENSW Thunderstorms (and speculation about Ex-TC Owen) - 13th to 17th December 2018 [Re: Nature's Fury]
Squeako_88 Offline
Weather Freak

Registered: 23/09/2005
Posts: 504
Loc: Elimbah 4516
Yeah it looks like EC in tonights run has delayed the SE turn of Owen by a day and doesnt have enough time to travel SE far enough... see what it says in the morning.
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