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Above: Maximum temperatures (left)
and departures from normal (right)
Below: Minimum temperatures (left)
and departures from normal (right)
Bottom: rainfall for the week ended 9am today. BoM  |
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 Heat
continues
The heatwave that has gripped the southern two-thirds of the continent
since Christmas Eve continued today, with a huge area of the continent
(shaded brown or dark red in the top left map) recording top temperatures
above 42°. Cooler southeasterlies gave the WA South
Coast some relief, while the passage of a weak front kept TAS temperatures
closer to normal.
The highest temperatures were around the meeting corners of NSW, QLD, SA and
NT. Birdsville, Oodnadatta and Marree all recorded maxima just over 47, while
in the NT Jervois reported 46.0 and in NSW Tibooburra reached 44.5. The temperatures
recorded in this area today and for the past two days have been within 2 or
3 degrees of the all-time records.
Night time temperatures across inland NSW, QLD and SA have become increasingly
oppressive as humidity has increased, with a slow diffusion of the moist airmass
that gave Central Australia heavy rain before New Year. A strong upper ridge
continues to suppress any welcome thunderstorm downdrafts, and
a very
weak surface pressure pattern is keeping winds light or calm. The combination
of these factors has slowed cooling rates after sunset, and those areas shaded
yellow to pink in the minimum temperature map (centre left) that had minima
between 24 and 33 degrees actually experienced temperatures in the 30s
to low 40s for most of the dark hours.
The dominant upper ridge has also produced a virtually rainless week over
an unusually broad area of the continent. Apart from the intrusion of rain
across the Centre and western SA at the end of December, very little has been
recorded across the southern two-thirds of the country.
 Cold
water greets
Sydney swimmers
Classic hot Christmas/New Year holiday weather in Sydney has filled
the beaches, but swimmers are not staying long in the water. Water temperatures have been
up to 5° below the average, with 16.5 recorded at Bronte and 18 at Clovelly,
yet the Manly Hydraulics Lab buoy, 13km east of Manly, has reported more seasonable
tempertures varying between 20.8 and 22 through the day, temperatures confirmed
by satellite imagery. The cause of the colder inshore waters has been local
upwelling after days of persistent northerlies or northeasterly sea breezes.
Ben Matson, a surf forecaster with coastalwatch.com, told the Sydney Morning
Herald the upwelling
effect displaced the ocean's surface water with colder,
deeper water. "People associate northerlies with warm weather, but it
actually brings colder water temperatures. We need a solid round of southerlies," he
said.
Big swells
continue on SE QLD coast
On the QLD Gold Coast, it was big waves rather than cold water keeping
swimmers on the beaches. A High in the central
Tasman Sea and a Low drifting slowly west into the Coral Sea from New Caledonia
have maintained a strong east to southeasterly flow across southern QLD for
nearly a week, building a consistent 3m swell.
News sources: SMH, Courier-Mail |
