Wide Bay & Burnett Chase

January 31, 1999

Chasers:Ross Portas (driver), Anthony Cornelius and James Chambers (wrote report).

Time: 10.30am - 9.15pm --- 10hrs 45mins

Distance Traveled:798.5km

It is certainly disconcerting heading out for a chase in Eastern Australia with a mod-fresh SSE wind blowing.  The night before, the coastal trough moved through with  isolated thunderstorms ahead of it. However, the inland trough remained, and more importantly, a vast upper level trough was approaching. We planned to chase somewhere N or NW of Toowoomba where LI's were expected to reach -8 by 4pm EST. The official forecast was for heavy falls with developing showers and t'storms.

We left Brisbane just after 10.30am and headed out towards Toowoomba. We reached the city at 12.15pm without any slight hint of a t'storm. In fact, conditions couldn't be much worse with a 20-24kn SE wind blowing at the top of the Toowoomba Range. We had passed through a few brief showers but these were only stream showers from Moreton Bay - not the type of precipitation we wanted. At least conditions were quite warm at 28C and 60-65% relative humidity. In Toowoomba our aim was to access the Internet for weather data, but that was harder than it sounds. We first tried the University library only to find it closed and then we tried the public library and were told only members could access the Internet. The librarian did however point us to an Internet Cafe.  Our $3 worth gave us  time to check out the situation. Nothing had developed, but forecasts and soundings still pointed to scattered t'storm activity later on.

With very little happening, we stopped off at KFC for lunch and to discuss our options. We decided to keep going west towards Oakey and then if nothing was  happening, out to Dalby. When we got back to the car, we finally noticed some large cumuli development indicative of storms and we all felt more at ease. As we drove WNW from KFC there was a rather disturbing development. Ross decided to put his Abba CD in - on high volume too! I became aware that Anthony didn't mind.

We passed Oakey and as we approached Dalby a weak anvil and large cumulus development came into view.  We stopped in the town as steady rain fell. It looked  very weak but we checked the AM radio and there was only very occasional static, but at least it was something. We had to decide then if we wanted to try going towards Kingaroy (150km NNE) where stronger storms were likely to form or hang back and hope this shower would turn into a storm.

The trip to Kingaroy showed some quite promising cumulus congestus build up and several times we passed under them. One had very large raindrops and I thought to myself that perhaps hail was possible in later storms. However, none of the structures looked like future storms and in desperation we continued north from Kingaroy.  A large area of cumulus congestus was situated to the north, and when we came to an intersection going onto the D'aguilar Highway, the congestus had  obviously intensified into a storm, and a fairly strong anvil had appeared. The static had increased on the radio, so we went after it. Finally at 4pm, after five and a half  hours we had found a storm!

As we drove NNE two CG's were observed and it appeared the storm was strengthening as we got near it.  Soon after, I spotted a storm to the south, which we guessed was the earlier Dalby shower that had become a storm also. Nevertheless, we continued north and soon the sky was much darker and rain had begun to fall.  The road was the only one that could get us close to the storm, so we continued and went through the very edge of the rain curtain. Things then started to get very interesting. The rain become torrential so at very slow speed it was impossible to see, and the lightning was increasing. Soon, we had to maneuver around a couple of  tree branches that were obviously brought down by the storm's outflow. As we made our way out of the rain curtain, CG bolts were coming down regularly and then...pea size hail starting falling. It was lucky we were on the edge of the curtain, because marble hail and possibly  severe winds were likely further into the core of the storm. It was now 5pm and we drove for two minutes to get ahead of it and take photos and video. A curved  gust front with a band of green above was edging closer, with whitish hail shafts bending under it.

The rain/hail curtain exhibited a 'rainfoot' which indicates a probable microburst. Then we saw an amazing sight. As several CGs hit the ground around us, a cloudbase lowering came into view several km away, but we couldn't spot rotation. Most of that motion was cloud moving in one direction only to be replaced by continuously forming cloud. That cycle was repeated several times.  Unfortunately as the storm moved northward, its lowering started to disappear behind nearby hills and we had to find a road where we could view it again.

The storm picked a nasty area to move into. It was an area devoid of roads. Looking for a road west, we drove northwards and found a turn off to Murgon. We were happy to find a west tracking road, but it made us go too far west and we found ourselves in a very low contrast vantage-point on an old farm road. At 5.30pm the heavy rain and the pathetic road network effectively ended our chase. It was disappointing, but at least we got to see a strong and possibly severe storm.

As we drove to Gympie on our way home, a storm was damaging Dalby - where we had gone through the shower more than 4 hours previously. Flash flooding and  high winds caused fairly extensive property damage, including unroofing several buildings such as houses and part of the local primary school. During the night,  several strong thunderstorms affected the region dumping high intensity rainfall and causing many blackouts.

Report by James Chambers