Brisbane Valley Supercell Hailstorm

November 4, 2002

Another trough was moving into Southeast Queensland…and once again there were several things going against the general situation.  Not that in this case they were huge factors, just little things that made you think “I wish there was more…” and so forth.  The initial problem (and something that has seemed to perpetually plague Southeast Queensland this storm season) was the possible lack of moisture.  Low level westerlies were a risk, and could potentially dry things out.  Furthermore, there was a thickening cloudband to the west (too much moisture in the upper levels, too little in the surface!  Too bad we couldn’t swap the relative humidities around).  And then shear was somewhat to be desired (although not all together absent).

It was warm and humid in the morning, but generally cloudy.  I had an exam in Toowoomba (2hrs west of Brisbane) at 9am…I finished just after 11am.  It was a little distracting watching sunny breaks and ACCAS float by every so often, so I was happy to finish!  I had more exams to study for, but I decided that if anything would develop I would chase around Toowoomba, although not venture as far as I normally would.  At around 11:30 it was still quite cloudy, but it appeared to be clearing just to the west.  By midday, it was totally clear!  I wasn’t too sure whether to be happy or concerned, as I didn’t want the clearing of the mid level cloud to mark the trough line – especially since winds were now tending towards the WNW (eeek!)  I had booked a cabin for the week so I could study in Toowoomba for the week (less distractions, less travelling time for exams).  I was just sorting my things out, and thinking about lunch when it was starting to get rather warm.  I decided to pull the curtains away from the windows to let some more air in…the wind I chose looked towards the SW, and there was a line of freshly developed TCU that had just gone up!  I quickly grabbed the video and camera, and jumped in the car and decided to head just south of Toowoomba.

The line of TCU seemed to be marking the trough line as it was quite defined, the first TCU that I saw developed into a nice little pulse storm that ended up giving some golfball hail and six inch haildrifts to parts of Nobby and Clifton! 

This was almost surprising given the storms had no structure to them, but I put that down to dryness.  The only thing I thought of was severe winds at the time, due to dry mircobursts.  Sure enough, there was no shortage of rain feet from the storms!  The odd thing was, with the storms to my west I had a light westerly – it is certain odd to see storms develop in a westerly, I guess it is testimony to how unstable it was even with the dry air encroaching at the surface.

The storms appeared to be heading NE, so I headed back north towards Toowoomba – I got some light rain but some very gusty winds up to 70km/h or so!  It was odd having such strong winds with such little rain, normally it pours down.  There were also some very spectacular CGs, not all of them on tape though (doh!)  But I got a couple more just south of Toowoomba. 

I headed east towards Gatton and sighted some massive rain feet again just to my north, the foot was extended several kilometres from the rainshaft and then was pushing in making an inverted rainshaft another few kilometres further west of there again. 

There were some awesome CGs striking just north of Gatton, I ended up stopping just north of Gatton and taking some video.  I only took about ten minutes but got heaps of CGs on video!  Unfortunately, I wasn’t watching where I was videoing, so I kept videoing too high sometimes (I was parked on an awkward angle, so I kept forgetting to compensate for that). 

Still, was great to watch and try and ‘catch’ some of the CGs!  I headed further NE towards Esk, I nearly hit a tree across the road (it had been pushed off somewhat, but there was noway to really swerve that hard and miss it).  Further north, there were plenty of small trees down across fences and heaps of branches across the road!

After not seeing lightning for a while, I got a fright when the interior of my car lit up just SW of Esk followed by a massive BANG about a second later.  I got even more of a fright when the exact same thing happened just seconds later, two awesome flangs in a row!

There was a lot of water around Esk, while the main storm had gone just to the east, they had just had some heavy rain.  I headed just north of Esk by a few kilometres, stopped at an advantage point and looked around.  The storm had a nasty look to it (although not spectacular, just nasty!) 

I got out and took some footage, then looked above me, a rotating base!!!  I won’t say exactly what I said, but I actually moved further north (I didn’t fancy being directly under a meso), I was still very close though – too close to really get proper footage of it, hopefully the SLR photos will show it better as it can zoom out more. 

There were some fairly spectacular (and close) CGs!  I sat in the car and videoed, I got my closest ever CG, it was only 50-60m from me (although far from the most spectacular I’ve seen), so close it gave a ‘crick’ rather than a ‘bang’!!  Several more close CGs followed, was awesome! 

The main storm appeared to be heading to the NE, eventually I got some gusty winds and heavy (but not torrential) rain…soon followed by small hail.  I pulled over again to video the hail, there wasn’t heaps of it and most of the stones were around 1-2cm with a few 3cm stones also. 
 

The winds were very strong though, and coming from behind, so they were smacking into the back windscreen!  I got concerned and turned the car around to face the wind (because the front windscreen is a bit stronger), the hail bouncing along the ground was quite cool to watch! 

I didn’t want to head further NE, doing that would mean going through the main core of the storm and also lead me too far away from Toowoomba where I needed to be to do some more study.  Instead I headed back south, where I got some more hail again near Esk, and I sat just south of Esk for a while. 

Yet another storm moved over and gave more 1cm hail!  (I lost count of the individual cells that kept developing towards my SW just NE of Toowoomba and moved around Esk dropping hail).  I had to laugh at the way people parked their cars…normally most people move their car after parking it on the footpath to protect it from hail, but storms kept moving over that were dropping hail so people decided to leave their cars on the footpath underneath the shop awnings!

More nice CGs followed, before I eventually decided to head SW again to vaguely head in the direction of Toowoomba.  Some awesome sunlit mammatus developed underneath the storms and made eventually for a nice sunset! 

I sat just west of Minden and watched some nice lightning off to my NE from the storms, quite a few CGs and heaps of crawlers!  Only I was on the wrong side to see most of the crawlers…but I couldn’t stay for long, eventually it was time to head back to Toowoomba and do the dreaded study (although was very difficult trying to peel myself away from the storm).

I must say that I was very surprised of the storm developing a mesocyclone given the shear…although the original initial updrafts did show a bit more shear than was forecast.  And certainly as the storms headed eastwards, they would have been able to interact with the seabreeze front which have been notorious for producing supercells before!  Certainly some of the best daytime lightning that I’ve ever seen!!!