Storm Chase 14th February, 2003

I awoke this morning to find a cloudless sky with temps around 22 degrees. There was moisture haze to the north and by 7:30 there was small cumulus forming on the top of Mount Cootha range. By 8:30 the sky was filled with cumulus however,each one lasted no more than about 2 minutes. Over the next few hours the amount of cumulus decreased until very little cloud cover remained. DP's by this time were around 19 degrees and the temperature was already heading towards the 30's. By 10:00 there were a few good cumulus congestus forming to my south around the tamborine mountain basin area. These like the other cumulus died off quickly and got replaced by others.

I knew today would be a good day for severe storm development because a trough was lingering about and yesterday provided some good moist north easterlies. There was still plenty of moisture around from yesterday's severe storm to fire off some activity. At 12:40 activity was starting to occur around the New South Wales area just west of Yamba. Light precipitation also started to form around the border ranges which was the beginning of the storms development. The DP had dropped earlier during the day, however it had now gone back up to 18.6 degrees and the winds were starting to pick up. By 1:00 there were scattered thunderstorms throughout northern New South Wales but there was still no activity on the local radar at this stage.

By 1:15 the sky was fairly cloud free with only low roll cumulus scattered around the place. The dewpoint still continued to rise to 19.0 degrees and by 2:00 the first storm appeared just outside of Beaudesert and was a pulse type of storm that slowly moved north. From my view I watched its updrafts explode upwards showing its crisp anvil. It continued to grow at a very fast rate with some mammantus forming underneath the anvil during the early stages.

Massive updrafts built up the western flank of the storm which merged with the main cell. By 2:20, distant thunder was heard from the storm which was growing blacker by the minute. 10 minutes later, the anvil had a weaker look however, a new explosive updraft punched through the cumulus line again on the western flank to replace the main cell. The anvil by this time was facing north east and the storm was slowly starting to move. Small amounts of static was starting to be heard on the AM which indicated there is probably lightning starting to build up.

A smaller cell started up just outside Ipswich at around 2:35 which showed pink on the local radar. The cell which was at Beaudesert split in two and one section moved slowly northwest. The Second cell outside Ipswich continued to grow slowly with mostly yellow and some pink on the map. The temperature at 2:50 was 30.6 Degrees in Archerfield, with a DP of 18.4 and the wind was ESE at 20Km/H which by then the static had increased to an average of 1 every 6 seconds.

By 2:50 the anvil of the storm just to my south outside Ipswich was starting to become fibrous and I agreed that it was starting to weaken. When I had a look at the radar map, it was only in the blue region. The 2 cells from the Beaudesert were starting to gain intensity with the top cell moving northwest and the bottom cell moving north showing mostly yellow and some pink.

The two cells merged outside Beaudesert to show some good rainfall activity on the radar image. The Ipswich storm weakened considerably over the next 10 minutes and the rate that this activity was going, severe storm development didnt look too promising. As this storm collapsed, an area of 100mm/hr of rainfall appeared on the radar.

The storm started to intensify again because the north-easterly winds had picked up again and mammantus was once again shown underneath its anvil. The storm continued to move northwest and the second cell continued north but weakened as it did.

 With the likelyhood of any severe storms low, I receiced only the occasional radar update just to make sure there was no more activity going to build up.

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