Michael Thompson's Australian
Storm Chase Diary
8th February
2002 - Severe storms in Illawarra
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The
beginning of 2002 has been a roller coaster of weather in the Illawarra.
In early January we were still in a prolonged dry spell which started
in December 2001 with bushfires threatening the outlying suburbs of the
city. Then came a week of relentless sapping humidity but little rain.
Then finally heavy rains and cooler temperatures. Even some flash flooding.
About the only thing missing was a decent storm. However a trough system
that had brought rain was finally moving eastwards for the 8th February.
Today
was a textbook storm scenario, pre trough cloud and rain had cleared seaward
overnight. But not before giving a spectacular lightning show about 75
kms offshore the Illawarra at around 3am , with constant lightning. The
morning revealed clear skies, high humidity and climbing temperatures.
A trough was located about 150km westwards.
The
first convection occurred down towards Canberra as the trough line passed.
By 1pm cells had popped up over the Illawarra escarpment. Rock hard anvils
indicated strong convection.
By
2pm a severe storm warning was in place as large hail was recorded at
Robertson.
I
was stuck at work so this was not a chase as such. But I did get to take
a couple of photos from work.
The
main feature of the storm of interest to me was the horizontal wind shear
along the storms outflow boundary. The differential movement of scud from
NE and a rain/hail curtain approaching was the best 180' shift I have
seen butted up against each other. It was NOT a mesocyclone, but it was
the strongest shear I have seen for a while.
The
storm brought heavy rain but little wind to the Wollongong City centre,
nut it was evident that the storm core was located about 5-10kms further
south. Hail was recorded at Berkeley. A second storm developed around
4pm and was more lightning active.
CHARTS
BELOW - Wollongong is located approx where 34'S intersects the NSW coast.
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