Sunday 20th of November 2005
Chase Duration: 5 hours
Chase Distance: 370km
Report By: David Findlay
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Chase Report
The storms developed over the border ranges and moved north throughout the day. The storms produced strong winds, widespread hail on the southside of Brisbane and an impressive gustfront. We began our chase departing Redcliffe at 1:15pm. We used two vehicles in convoy, communicating by UHF CB radio. By this stage the storms were already well developed just south of Rathdowney and Killarney, moving slowly north. The line extended from near Canundra in the east to Killarney in the west and was already visible from Redcliffe.
We departed Redcliffe at 1:15pm and headed down the Gateway Motorway to just north of Beenleigh, near the Logan Motorway interchange. Because of the massive anvil and some haze that stretched out to the east, it was difficult to see exactly where the main cells were until we got as far south as the storms were. From there we headed west along the Logan Motorway until reaching the Mt Lindsay highway and then we headed south towards Beaudesert. Due to the high number of trees along the road it was hard to see the storm most of the time, although we were able to spot huge updrafts going up. South of Park Ridge we noted quite strong northerly inflow winds, about 15-20 kts. There wasn't much lightning that we could see at this stage, but it was noisy on the radio.
Reaching just north of Jimboomba the winds really started to pick up, this time blowing away from the storm. We started getting hit by big heavy raindrops, so we turned around and started heading back to the north to try and get ahead of it. Jumping back on the Logan Motorway heading west again we spotted a massive high based gust front on the front of the storm. It looked very turbulent and the cloud above was quite green. We pulled off the motorway into the Wacol Industrial Area and found a spot where we could stop and see the storm. Within minutes of our arrival the outflow winds picked up and were blowing dust and debris everywhere. Dust was picked up for blocks around us and carried 50 metres in the air. We jumped onto the Ipswich motorway and tried to get away from the gust front to the north.
We then continued up the Centerary Motorway while being hammered by 40kt gusts that were bringing down heaps of leaves and branches from the trees. We then went halfway up Mt Cootha, just past a channel 9 reporter who was filming. The gust front seemed to continue north over the northern suburbs, while the storm core took a strange left turn and seemed to go behind the mountain before heading north again. We left Mt Cootha in a hurry as it appeared that the heavy rain and hail was about to arrive. Looking back it seems to have swung around and completely missed where we were. We headed from Mt Cootha to Toombul shopping centre roof and the winds seemed to have eased by this time.
From the roof of Toombul shopping centre we were able to watch the cell move to the north, with a very long inflow band coming in from the east. The clouds in the inflow band seemed to be moving at least 30-40 km/h. There was infrequent lightning and a few clear air CG's. The original gust front had detached and formed a roll cloud which moved out over the northern suburbs into the bay. After about 30 minutes on the roof of the shopping centre, not seeing anything else coming from the south, we decided to chase after the main cell as it headed west of Narrangba. We eventually reached it out the back of Woodford, and took some more video of CG's. No structure was evident by this point, but there was frequent lightning which we videoed. At this point we decided against following it further and headed home. All in all a pretty good day's chasing.
