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.
Radar