![](media/20000429_850.gif) |
Warm air sweeps down
from the north and northwest over eastern states, while colder southwesterlies
flood over WA in this map showing the situation at the 850hPa or about
4,500 foot level at 10pm EST. Wind barbs show direction, with the
strongest winds colour-coded orange to red. Shaded grey areas show
high humidity and probable low cloud areas, while the lines (isotherms)
show the temperature at about 4,500 feet, away from the influence
of the ground or water. The freezing level isotherm is blue. Note
the strong thermal gradient about the front in southeastern SA, where
only a few hundred kilometres separate air at 12° from air at minus
3. |
The active cold front that swept through
southern WA yesterday crossed South Australia today, raising dust
with gale force NW winds, producing a few thunderstorms and around 35
to 50mm of rain about the Adelaide Hills and Kangaroo Island
in the 24 hours to 9am Sunday. The Adelaide Bureau of Meteorology office
in Kent Town recorded 20mm between 6 and 9pm with the passage of the front.
Further rain overnight brought the 24 hour total to 31.4, the highest
April 24-hour fall since the Bureau moved to Kent Town in 1977. Falls
were heavier in the Adelaide Hills, with Mt Lofty summit recording 53mm.
Flash flooding was reported. Raised dust and dust storms occurred in southeastern
SA and western Victoria as winds gusted to 80 or 90km/h. Parafield
Airport, north of Adelaide, was closed when dust reduced visibility to
a few hundred metres, while downed trees brought down powerlines giving
blackouts in some areas. The highest reported wind gust was 106km/h at
Cape Willoughby on the eastern end of Kangaroo Island. In the Mallee and
Wimmera districts of northwestern Victoria, dust storms were said to be
the worst in more than 15 years, cutting visibility on roads and making
sporting conditions difficult.
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Minimum temperature
variations from normal |
Ahead of the front, overnight temperatures
in SA, Vic and Tas were up to 10 or 11° above average. Adelaide's
minimum of 21.7 was its warmest night recorded so late in autumn,
while inland, Naracoorte and Keith only dropped to 20, 11 above normal.
Even Strahan on Tasmania's west coast only got as low as 18. Behind the
front in Western Australia, overnight temperatures were 8 to 10
below normal. 4.8° at Lancelin and 4.0 at Kwinana, both near the coast,
were more than 9 below. Perth Airport's 4° was its lowest April minimum
since 1971.
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