Storm chase report from December 4 2007840km chase run: After Katherine’s two previous days of massive lightning and storms from the trough Nick Moir and I decided to go down for perhaps a third event. All the numbers were huge, CAPE at over 4800, LI’s at -8+, humidity and temps were great 38c and 24 for DP’s. Quite high but the humidity right through the morning ranged from 87% but slackened off to around 50% when we arrived, still quite good. Upper temps were around -7C at 600 which was ideal for this storm to get going. The storm that we encountered at a top reaching
23km and something about 50DZ which is attributable to hail or something..
The upper level cloud cover had finally burnt off and cumulous were slowly but surely converging into the area we were wanting. BoM was 60% confident of something happening, but not to the extent of the last few days previous.
Radar obs showed storms building to the SE but a convergence line was forming to the W/SW. GIF wind profiles had convergence lines to the SE and also in that area. We headed out to Tindal airport to get some clearer air for the obs and for cloud observation and it was not long before we decided that heading west toward Kununurra was the best option as the storms that were pulsing were tracking that way. We calculated that the Victoria Highway was smack bang where we needed to be to intercept the cell. We were about 140km from the actual system and could not determine what was happening as we could not see the cloud bases. The closer we got we saw cells pulsing with pileus and still rising – a good sign – especially when they were at the front of the storm. This showed us that the cell was healthy and with plenty of fuel gathering within. We reached the storm and it was beautifully organized. Lots of warm inflow. We stopped at several places to get some structure shots and there were plenty of strong CGs. We backtracked towards Katherine to get around to the inflow region as the location we were at was getting too much precip coming our way..
We found a great spot next to a large antenna tower and that’s when the beast exploded! We were taking shots outside and the inflow was alternating with outflow – excellent mixing of both, warm air pushing behind us into the cloud and then cool outflow air facing us – quite odd! We noticed the cloud and rain shaft turning a dark green which was awesome to view, so we decided to core punch the thing to see what was happening inside. Then the wind picked up as we approached and within a few minutes it was pelting down – the winds we estimated were at least 80-90kmh due to small branches being ripped off trees and flung across the road as we drove and lots of leaf litter making things difficult. We had to slow down the driving speed as the water on the road was atrocious, no aquaplaning for me!. Several older but large trees were felled along the way. Hail fell as we pulled over to a side road to get some photos of strong CGs. The hail was minimum 1-1.5cm in diameter. It was surely at least 2cm in the core on the other side. Driving out of the core we encountered another outflow region with the same results. Two separate microbursts with hail.
Lightning had started a great scrub fire on the side of the road on the way back to Katherine and we got heaps of great shots of us both in the thick of the flames getting photos. Added to that mammatus had formed above us which was a nice treat. Nick is a pyromaniac and was just throwing himself into the flames, waiting for the wind to pick up from the outflow and whip up the flames, I got some great shots of him in the thick of things.
The storm lulled a little so we fuelled up back in Katherine and checked the obs again and decided to head north to intercept what we saw was a separate right mover detaching from the main system and heading for Pine Creek.
Our timing was to get to the lookout and get some lightning. We reached the lookout around 6:30pm and set up, the storm was still in the throws of weakening a little and there was only zits of lightning – no new pulse towers formed in the inflow and it must have got caught up in dry air as there was no more movement of the storm. The anvil was fibrous on the eastern side, but on the western side it was a bit better structured and most of the lightning was on that side of the storm.
After about an hour of waiting we decided that was it and headed home. On the way the cell fired up again and was throwing out some odd angled CGs. We desperately tried to find an opening in the scrub to get some photos and found a side road and did a U-turn and faced the storm. Not having anything to focus on was a real pain and just as soon as we set up the thing died – ironic to say the least.
No complaints from us as far as the chase went. We got all the attributes of a very severe storm and personally finding hail that size in two separate areas of the storm was excellent. I did not get any CGs unfortunately, in fact Nick only managed a couple – that’s how fast they were striking!
I’ll have to down load a bunch of photos to the forum later on as all my storm shots are on his laptop as I wanted to make room on the card. Will do that later on as we’re heading out again to chase down at Jabiru about 240km to the SE. Goss from BoM is that around 1pm we should see some squall lines develop, they won't reach Darwin they say which will peeve a few chasers up here!
The photo's are worth the wait and Nick is pretty happy with what he's found thus far as far as tropical storms go, he was stunned to see how much CAPE and the like we have, he mentioned that with those numbers in NSW they'd get huge supercells.
Mike
