Topic: NSW & S Qld Severe Storms: 19-23 September 2008

[David C]

GFS going for a 2nd consecutive weekend of severe weather across the east. Once again we could see some very solid flow through through the mid levels, along with some strong early-season instability.

It will be interesting to see how Friday pans out in SEQLD. As of now, GFS is clearly favouring quite rich boundary layer moisture with dewpoints in the mid-high teens finding their way south in time for Saturday afternoon. The disparity between GFS and LAPS is still evident for Friday but not as great as the previous weekend. Far from a sure thing, but it will be worth watching.

[nmoir]

   looks like narrabri is the hot spot for sat arvo. last i saw was saying cape over 2000 .
wish i could be there.

nick

[Jimmy Deguara]

Hi guys,

It seems the models can't seem to make up their mind on positioning but I am not as enthused by the prospects of spenidng hard earned dollars for a northern NSW intercept. Sure there will be severe storms likely but the distance just does not add up to the value one would hope for. I have wedding stuff to do so I am a little biased though haha!! At least for those wanting to chase a few onsecutive days, this is one way to see the countryside.

I will reassess Saturday morning.

Regards,

Jimmy Deguara

[Michael Thomas]

I think things are looking pretty good for storms over the next couple of days. It is quite encouraging to see 16-18 C dp's sitting north of Gympie. Even west of the ranges moisture is not too bad with 14 C dp's around Moree and Miles. As long as moisture doesn't mix out with we should be looking pretty good, moisture wise, despite the NW winds forecast on Saturday. On Saturday, mid and upper level winds look quite nice, however, the W to NW surface winds will not be doing any favors. Forecast sounding currently show a pretty strong cap on Saturday morning over the NW slopes. It should break easily enough though with strong heating during the day. If were to pick somewhere now I would have to say around Moree since moisture should be there. Mid-level winds are stronger to the south but with the NW surface wind I feel this will only mean storms will move faster. Storm mode I would say will be multicelluar possibly developing into a squall line later as outflow boundaries merge. Another area of interest may be the border ranges, directional shear should be better due to N'ly surface winds, also it appears lower level moisture should be adequate there.

Michael

[Rodney Wallbridge]

Gyday everyone, GFS shows a slight offset convergence on the Richmond Range 1hrs drive west of here this arvo. I am a bit put off by the lack of sfc windspeed.Mid level winds look quite nice today to push it over closer to the coast where hopefully a better feed will be waiting.On past occasions where by high Li's and median Cape and really only Orographic trigger is certain.... a stronger sfc wind might be needed. An increase of these winds produced by strong updrafts will keep these cells alive today.
I'll be out and about after work.... hope the storms wait for me

[Steven]

I'm almost drooling over the -8 LI and 2600 CAPE on the 18z 4PM run for Saturday, if that's anything to go by, very good instability!

Not sure about our chances here locally however... Maybe Sunday onwards?

Steven

[Shaun Galman]

Hi all,
I hope we manage to get in the firing line out this way this time lol.

It's currently sitting at 30ºc now (12:00pm) and looks to be a fair bit of mid level moisture with the sky looking almost white with moisture haze. Some cumulus seem to be appearing just now to our north. If I were to hedge a bet here, I'd say we were just a little too far west for action but anything is possible Looks like this trough line has started up near Thargomindah (QLD) so it's slightly possible that we may get something come down over the border near us if the trough hangs around long enough into this afternoon/evening. It seems to pretty rapid moving but it is pretty widespread to the SW of QLD and dipping into the far W of NSW near Tibooburra, from current satellite obs.

Cheers guys, take care if chasing today!
Shauno

[Michael Bath]

The main cell over SE QLD (Kilkoy) this afternoon has been exhibiting a very interesting Doppler wind return for several frames now. Quite a decent mesocyclone on that storm - though we are looking a couple of ks above the surface that far from Staplyton radar.

EDIT - updated warning - large hail reported:

Issued at 6:00 pm Friday, 19 September 2008.

The Bureau of Meteorology warns that, at 6:00 pm, severe thunderstorms were detected on weather radar near Kilcoy and Mount Kilcoy. These thunderstorms are moving towards the northeast. They are forecast to affect the area north of Woodford by 6:30 pm and Conondale by 7:00 pm.

Damaging winds, very heavy rainfall, flash flooding and large hailstones are likely.

Thunderstorms today have already produced damaging wind gusts, large hail, and rainfall of 28mm in 5 minutes at Kilcoy.

[Carlos E]

28mm in 5 minutes. Wow. >_<

That's like all my July/August rain in 5 minutes.

[Steven]

Thanks for that Michael, no doubt there was severe conditions under that cell, it was black for almost an hour on radar.

I was beginning to worry whether it would come over or not, but it has dissipated.

[nzstorm]

Greetings,
Good to see some decent CAPE being plotted by the GFS so early in the season.  Will watch todays instability with interest.

[Michael Thomas]

That was a decent storm in SE Qld, quite decent structure. EL was pretty low yesterday so the storm wouldn't of had much height but it still packed quite a punch. Anyway, for today, I feel dp's are not going to be as high as GFS has them west of the ranges. Lower level moisture really took a beating yesterday out there with the dp getting down to 6 C. In fact the 12Z Moree sounding was looking very dry. Overnight, dp's have recovered though I don't see them getting past 15C in a hurry. I guess the 0Z sounding should be good in determining the moisture depth out there. With 30/15 CAPE should be more than sufficient. East of the ranges in SE Qld I have absolutely no concerns about moisture and with the cooling aloft I feel pretty confident in saying CAPE should be quite decent. I think CAPE could approach 2000 j/kg, maybe greater locally. Just wish the mid level winds were a tad stronger. Good luck to those heading out.

Michael

[Jimmy Deguara]

My feelings reiterated Michael.

I doubt even the dew points west of the ranges would 'be' in the mid teens. I think mixing will occur and the dew points will drop. I have decided not to head out. Good luck to those on the north coast and for those who chase in Queensland. I think this is a NE NSW day for chasing.

I will be investigating what may have happened with GFS this year - that's two weekends and two events it has stuffed up - not that this has not occurred in the past.

Regards,

Jimmy Deguara

[shanesmp]

Appreciate your opinion guys. I'll be heading up to Armidale (As base) for tomorrow and monday. I am hoping for a further moisture increase from 14c DP's to about 16, but looks good regardless. Monday has some rather impressive shear and some turning on the plains. Hoping for a big one!

*A very excited Shane*

[Carlos E]

An impressive storm on the Grafton radar just a little west of Casino in N-NSW atm.