Topic: NE NSW / SE QLD Severe Thunderstorms and more flooding : 4 - 8 Nov 2009

[Paul D]

Nice shots, and looks like you a buzz of a chase James and Macca. Know someone who's off to fix dents & sounds like you might need it!

Radar interaction looked interesting, though there doesn't appear to be much defined onscreen rotation on the Doppler,
Interesting contrast at the Nth edge of the Cell that was NE of Dalveen at 3:55 UTC-4:19UTC

Cheers
Paul

[Mathew Townsend]

Raining away here at Armidale. Got alot cooler and temperatures only at 14.5 degrees now. It will be one of last weeks for me staying here!

[Michael Bath]

Had regular thunder and lightning for the past 2 hours here. Some visible CGs amongst it with very loud booming thunder. Must be originating quite high up. Slow moving cells from generally the NE but not a lot of rain so far.

Any more hail pics James, or damage ???

[Richary]

Michael - I see on the radar at the moment the general rainfall pattern is moving in a southeasterly direction. However the bigger storm north of Jackadgery is bucking the trend and pushing NW. There is also a stationary one at Wooli and a couple off the coast further south that appear to be forming and moving against the general flow as well.

I am guessing there must be quite a bit of shear up there at the moment, though it doesn't look that obvious on the latest Brisbane or Moree soundings.

[DanTheMan]

I was heading for Toowoomba/Warwrick but came across some sweet convection west of Kilcoy-Esk, so regrettably hung around there for the day. Although I saw some good storms, nothing compared to the beast's down south, I have learned my lesson though! Was worth the 500km I put in.
For my 1st real chase it wasn't bad, as I have said, many lesson's learned and look forward to applying them all next time to make for a better chase. Here's a few pics anyway.



Somewhere between Esk and Kilcoy


This one was taken just north of Blackbutt, some strong winds and intense lightning there, my phone crapped out as I spilled coke on it and had no radar, but managed to talk to Dad who got the radar up and told me a black core was heading for Blackbutt, but then it stalled and lost it a bit, should have driven west but couldn't find any decent roads heading the right direction.

[Chris.]

Location Warwick QLD 5/11/09


Hi, some images below as promised and it was quite an afternoon here in Warwick! Between the break in low level cloud you could see the massive towers forming directly above Warwick. This merged with a cell from the South and all hell broke loose.

I tried to stay on the southern side of it but found myself directly under it. I headed out Freestone Road (I must have been just behind Macca and James) and could see what lay ahead so I decided not to take the risk and went up to Mt Tabor instead, this turned out to be equally as dangerous.

To say this storm exploded is an understatement, I've never experienced anything like it.

There have been some serious fires in the region and the smoke is visible in the images, gives them an eerie cast as well.

Storms combining directly above Warwick. 15.16



This one is taken in Warwick CBD at 15.33, looking up the face of the cell moving slowly towards Allora.



In position on the North Side of Mt Tabor looking towards Freestone, Cunninghams Gap and the battering they were copping at that moment 15.33



This base formed in half an hour of the shot above and it was trowing out CG'S every few minutes with wide spread CC lightning. 16.01



Double strike over Freestone looking N/E 16.02



looking N/W as the storm exploded and lashed Allora. 16.08



I was keeping an eye out what was happening behind me and it suddenly changed for the worse. I quickly packed up and I was down the side of Mt Tabor so had to get back to the top. As a Keen photographer I couldn't stop taking photos so was stopping every few steps to take photos.

This one looking S/W and directly over Warwick. 16.08



Looking directly South the outflow at this point was unbelievable and at 110kg it was pushing me sideways and stinging pea size hail. 16.09



Turning around and looking again towards Allora to the N/W. 16.10



I knew I should not be where I was in the open so I  headed for the Car. This one taken on top of Mt Tabor looking to the S/E and it was green! 16.13



One final shot from the top of Tabor looking towards Allora again. 16.13



And last shot looking NE over Freestone. 16.14



Despite the damage the rain was beautiful for hours after wards and amazing amount of lightning.

Regards,
Chris.

[Michael Bath]

Thanks for that report Chris. Wish I could have been up there to enjoy it too.

Apart from the thunderstorms this system has brought very heavy rainfall again to parts of the Mid North Coast. 36-48 hour accumulations to 9am today (7 Nov) have exceeded 500mm at some centres. The heaviest falls have been in Coffs Harbour.

There are ongoing flood warnings current for the Orara, Nambucca, Bellinger rivers, and also Coffs Creek. A flood watch is current for the Hastings and Macleay rivers.

[Michael Bath]

Brisbane soundings for 5th November. The profile on the morning was impressive with significant instability up to 200 hPa and dry air aloft. All it needed was a boost in low level moisture and shear which occurred from the SE.




128km Radar Loop for Brisbane, 02:00 05/11/2009 to 15:00 05/11/2009 UTC





See : 256km Radar Loop for Brisbane, 01:00 05/11/2009 to 15:00 05/11/2009 UTC

[Chris.]

Thanks for that report Chris. Wish I could have been up there to enjoy it too.

Thanks MB, I am sure you would have enjoyed it immensely!

Thanks also for the readings, have got a better understanding of them now studying your thread Aerological Diagrams.

http://www.australiasevereweather.com/forum/general-weather-all-topics-that-are-not-current-severe-weather-should-be-posted-here/understanding-aerological-diagrams-soundings/


Regards,
Chris.

[Macca]

A few interesting things about that Freestone storm (let's call it that for now). When James and I were chasing further south earlier there was a strong outflow push from the earlier Tenterfield - Stanthorpe storm. This was concerning as it was heading north and it was quite strong. BUT...when we were just south of Warwick. You can see in the radar animation there were two little cells which fired up - one near Oakington and another near Killarney. The Killarney cell looked quite nice for a short while (shape on radar and visually) but it was undercut by the northward advancing outflow.

Another short while later, the Oakington Cell dissipated and the Freestone cell kicked off right on the outflow boundary (which was aligned east/west). It stalled in this region - I suspect due to the strengthening ENE'ly flow pushing into it. The storm then sits on this boundary for a LONG time after initiation (even after Allora gets nailed). You can still make out the boundary in the 6:06UTC image with the Allora cell on the western edge of the frame and the Freestone cell still sitting there NE of Warwick. Its not until just after that that another cell goes up in front of it, somewhat ruining the boundary interaction/storm development.

Certainly a very impressive set up. As has been mentioned, hail was definitely on the cards. You pretty much cannot rule out large hail on days where instability is as good as it was on Thursday - shear or no shear. Even if there was zero shear, there was enough instability to generate severe hail (>2cm). Add in 20-25knts at 500mb and the potential hail size increases significantly. Add in 20knts at the surface and it goes up again. Personally, I believe lower end shear events (such as this) in Australia generate larger hail than higher shear events. This is partly due to the higher shear events often occuring outside the "normal" storm season where moisture is often lacking (and hence instability). With the lower end shear events, the updraft is displaced just enough to get the hail to fall back into the region where it may get caught up in the updraft again for another growth cycle. In higher shear events, this tends to be more difficult because the updraft is too displaced to get the hail to fall into a "recycle" region. (There are exceptions to the above - if you have a high shear event with very strong instability, the updrafts will often stand up more vertically than the shear would normally allow and this is where the gorilla hail comes from...hehe).

Thursday's Freestone storm was a perfect example where the hail was just falling back into the updraft region and getting recycled several times. When we first encountered the hail it was early in the storm's life and was only in the 1-3cm range (guessing around the 5:00-5:12UTC images on radar). 10 mins later it had been through another cycle and was producing 4-5cm hail (guessing around the 5:18-5:24UTC images on radar). 15 mins later it had gone through another cycle and the hail size got into the 6-8cm range (around the 5:36-5:54UTC images on radar).

GFS appeared to nail this set up almost perfectly. Instability wise, shear wise, and precip wise. Pretty much right on it. It even picked up the boundary mentioned above.

Definitely a fantastic chase - I'd rate this in my top 3 chase days in Australia.

Hopefully I'll be able to get some more video up in the next few weeks to show some more of the structure in its early stages.

Macca