Thunder
Downunder 2001!
November 23, 2001
Back to Thunder Downunder 2001 Chase Reports Moisture was going to be today's biggest problem. A couple of days ago, an intense low had formed in the Tasman and had put most of the eastern half of Australia under a dry southerly airstream, this was going to have to change pretty rapidly if there were to be any chance of storms on this day!
Fortunately most of Queensland can get some rapid moisture return, which was the case - although moisture levels were still relatively marginal, and any storms on this day were going to have high bases, but that also brought the potential for dry microbursts/gust fronts.
The other problem was the cap, without the presence of a defined trough, it was going to be difficult to push something up, even with temperatures well into the mid and in some areas, high 30s - the cap was very strong with a warm layer at 850 well established over the area. 850 temperatures were pushing the high 20s in far western Queensland, but had decreased to around 20 degrees around the Roma area, and the low 20s over Charleville - certainly a tough situation and if anything was to develop it was going to be late!
There was some instability around, there was effectively a neutral airmass over the area, no upper trough and no upper ridge, sometimes in these situations when it gets very hot an upper level ridge will push into the area and inhibit convection, but this wasn't to be the case on this day fortunately, as there were already a few things that were going against the day!
Shear was relatively good though, although showing a little slack in the low levels, a 300-500mb jet was pushing into the area nicely for the afternoon and evening, and would ensure that storms would be relatively long lived. The lower levels weren't too bad though, 15-20knots at 850mb, but not much stronger until 500mb where it got up to 30-40knots. 300mb had a 70-80knot jet pushing into the region which was good, and possibly assisted in aiding a little vorticity in the upper levels.
The evidence of a cap was clearly evident in the sat pic sequence, with virtually no convection at 4pm (06z). But exploding between 06z and 09z (7pm), and continuing into the night with strong convection still present at 11z (9pm).
Report by Anthony Cornelius & Andrew McDonald, all captures by Andrew McDonald |
