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Above: As
the first cold front clears the NSW coast, a Low slips down the west
coast of Tasmania, rapidly deepening to 973hPa at 4pm EST. A second cold
front attached to a secondary Low moves in from the southwest to cross
the SA coast just before midnight. These surface charts are for 4am,
10am, 4pm and 10pm. BoM. |
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Above: IR
satellite hourly images (1300 missing). The cloudband that produced
yesterday's rain event flings out into the Tasman Sea , thickening
and broadening as cold air undercuts a conveyor belt of moist tropical
northerlies ahead of the front. Some of the cloudband wraps around
the low moving down the Tasmanian West Coast, while large blobs moving
eastwards across Victoria are huge cumulonimbus tops close to the head
of this classic mid-latitude comma-cloud. Behind the second cold front,
the cloud is relatively stratiform and unbroken at first, but becomes
progressively more speckled and cumuliform as it pushes northeast under
colder upper air. In the last few frames, white speckles in the centre
of this cloud field show that strong instability is pushing the cloud
tops into higher, colder levels. Weatherzone, BoM. (GMS-5
backup with GOES-9 operated by the joint effort of JMA and US
NOAA NESDIS over the Western Pacific)
Below: Aerological
diagrams showing the results of the Wagga balloon ascents at 9am
and 9pm EST Wednesday, 9am today and 9am Friday. The righthand
red trace shows temperature, read off the scale at the bottom,
against height, read off the barometric pressure scale in hPa at
left. The left red line shows dew point, and the closer the two
red lines, the more moist the air. The blue lines are ghosts of
the previous ascent. Wind direction and speed are shown at right.
Temperature in the lower 2km or so of the atmosphere drops by more
than 10C in the first 12 hours as the surface front moves through,
but upper winds stay steadfastly northerly ahead of the upper trough.
In the second 12-hour period, the upper thermal trough moves in,
dropping middle atmosphere temperatures by around 10C, lowering
the tropopause and swinging upper winds westerly. The dew
point trace in the second frame is smooth and close to the temperature
trace, showing consistent deep moisture in the rainband, but in
the third and fourth frames this
is becoming
increasingly patchy
with
dry slots as a wintry cumulus field is borne over Wagga on strong
westerlies. BoM
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The cold Southern Ocean airmass that has been sweeping into the continent
since Monday brought snow and strong to gale force winds to NSW and VIC today,
while maximum temperatures were 4 degrees or more below normal across almost
the entire continent apart from the NT Top End and Far North Queensland. Flooding
developed in eastern VIC in response to yesterday's heavy rain, and an ear-popping
low pressure system sideswiped Tasmania bringing heavy rain, flooding and hurricane
force winds.
 Heavy snow fell to as low as 700m in VIC and southern NSW as cold
air behind the main front overtook the trailing edge of yesterday's rainband,
giving
several
hours of heavy snowfall in the early hours of the morning. 15cm of level snow
was reported from Koetong in the Upper Murray Valley this morning, and the
Mt Hotham Road was closed after police had to tow motorists out of snowdrifts.
5cm was reported in Batlow NSW (780m asl), 10cm at nearby Kunama (1150m) and
30cm at 1400m in the nearby mountains.
Wintry showers in a strong westerly stream took over from the rain, bringing
further snow, hail and sleet through the day down to 500m in VIC grading to
around 900m on the NSW Central Tablelands. In VIC, the Bureau of Meteorology
weather notes stated snow fell down to the 500m level during the day, but did
not say where. Snow was falling at 800m on Mt Macedon and settling at 900m.
In NSW, 5 to 10cm with drifts to 50cm were reported in the Shooters Hill area
south of Oberon during the afternoon. Light snow, not settling, was reported
from Guyra, Murrurundi, Oberon, Orange, the upper Blue Mountains, and Yetholme
east of Bathurst.
VIC and NSW ski resorts enjoyed their heaviest falls of the season so far.
Thredbo NSW reported 15cm of fresh snow in the Village to 9am and a further
10cm to 3pm, while up to 50cm was reported at higher levels. In the Victorian
Alps,
recent warm weather, lack of snowfalls and yesterday's heavy rain had left
slopes
fairly thin, but
whiteout
conditions
today resulted
in depths of around 1m on Mt Hotham and 35cm on Mt Baw Baw by Friday morning.
 Flooding from yesterday's heavy rain worked its way down many eastern Victorian
rivers producing levels just above minor:
- Macalister: peak of 2.17m at Licola around 7am with minor
flooding downstream to Lake Glenmaggie
- Mitchell: minor flooding began late today
- Dargo: minor flooding began late today
- Ovens, King, Buffalo and Buckland: minor flooding
- Kiewa: peak at 3.05m at Mongans Bridge around 6am with
minor flooding to Kiewa
- Mitta Mitta: peak of 2.66m just above moderate around
2am. The low level of Dartmouth Dam prevented flooding from travelling farther
downstream
- Seven Creeks and Castle Creek: produced flooding
to about 1m above minor flood level around Euroa. Secondary peaks occurred
in both streams during the afternoon, possibly from melting snow.
- Acheron: Taggerty peaked at 2.38m around midday with minor
flooding
TAS bore the brunt of a dramatically deepening low pressure system
today. The low developed south of Adelaide and west
of TAS on Tuesday evening as a secondary on the cold front that cleared
the NSW coast this morning. A complex of weak lows with central pressure just
below 1000hPa remained nearly stationary west of TAS yesterday, consolidating
into one centre, 996hPa, just west of King Island at 10pm EST . In the next
18 hours, the low deepened to 973hPa while moving briskly down the TAS West
Coast, producing a remarkable 10-minute average wind speed of 124km/h at Maatsuyker
Island at 7pm, with gusts to 143km/h. Details of other strong winds across
TAS, VIC and NSW are given below.
Heavy rain fell on the TAS Northeast Highlands overnight
and this morning, particularly in the North Esk River basin. Mt Barrow recorded
118.4 and Upper
Blessington 73.0 in the 24 hours to 9am, while Mt Victoria recorded around
140mm in the 24 hours to 3pm. Major flooding was reported in the lower North
Esk, while minor flooding developed in the upper reaches of the South Esk,
the Meander, and lower Macquarie basin. Snow was reported from the Central
Plateau during the day, with Cradle Mountain Airfield reporting 3cm on the
ground at 3pm. Lake St Clair in central TAS had its wettest July day in 14
years of record with a total of 59.2mm in the 24 hours to 9am Friday. |
Records set
this day (previous record and years of computerised record shown in brackets):
Highest daily rainfall for July:
New South Wales:
072146 ALBURY AIRPORT 50.0 (43.1, 20)
074221 NARRANDERA GOLF CLUB 30.2 (29.8, 34)
Victoria:
080091 KYABRAM (INST SUSTAINABLE AG) 33.8 (22.6, 40)
081049 TATURA INST SUSTAINABLE AG 38.8 (34.0, 60)
082016 EUROA 61.0 (52.3, 115)
082138 WANGARATTA AERO 44.0 (27.0, 15)
083083 EDI UPPER 63.2 (46.2, 15)
088023 LAKE EILDON GOULBURN MURRAY WATER 101.2 (73.7, 114) (Only 0.1mm short
of the all time record)
088053 SEYMOUR SHIRE DEPOT 59.6 (55.1, 116)
088109 MANGALORE AIRPORT 56.0 (35.8, 43)
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