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A
thundersquall line passed over eastern Eyre Peninsula early
on the morning of the 30th and then headed across Spencers Gulf.
It passed over the east coast of Yorke Pen at around 7am,
weakening a lot as it approached the Adelaide coastline. It
prevented much of the storm activity in the Adelaide area
during the day by turning winds W to SW for a period and cooling
the temp down and stifling convection. This line then built up to
massive thunderstorms as it hit the Murray River, causing wind
damage, hail, and flash flooding in parts of the Mallee and South
East. This including 20mm in 14mins at Lameroo.
A large area of storms off Eyre Pen at 5am also spawned a more
massive outflow which did then initiate some weak storms over the
Adelaide Hills and north areas around 1pm. This all cleared to the
east soon, and a deck of altostratus and light rain kept temps
down although Dew points had climbed from 15 to 20 plus by now
from the rain.
A front following the trough approached Adelaide just on sunset,
and with nocturnal cooling of the cloud-tops, caused the front to
become a very thin Cumulonimbus line which moved east across
Adelaide and the hills. Isolated showers with rather large and
heavy drops came from this but no thunder. Then this frontal
passage seemed to instigate further uplift of the lower layers,
and further nocturnal cooling of these tops saw them explode
within just a half an hour to lines of storms everywhere from
Adelaide east and north. These in contrast to the just passed
quickly eastward moving frontal line, moved almost due south at
times, or at least SSE across Adelaide and the hills. After just
dropping heavy showers for another half an hour, they then started
to spark and form right up past Oodnadatta to the north, and east
into the Mallee as well.
At about midnight, Andrew Wall, Greg Spencer, Brendon Simmons, and
myself decided to chase a few of these small storms up in the
Barossa region with a view to going to the Riverland. We reached
just north of Nuriootpa where we experienced some nice close Cgs
and then a good view of the light show from the Truro lookout. We
decided to go down to Blanchetown and see what develops but it all
seemed to die by 2am and we headed home.
The heaviest falls occurred to the north and east, with Naracoorte
topping the official SA tally with 40mm, while continuing storm
activity overnight brought 66mm to Mildura just over the border in
VIC. The 24hr heaviest rainfall in years for that area of drought
VIC.
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