Cold Outbreak - Melbourne 15/5/99

Summary of events

Jane ONeill

MSL analysis courtesy of Bureau of Meteorology

(Nick Sykes - Ashwood - 10.48am Sat)
Well in the last 2 hours the temp in Melb has really started to fall. The wind is a very cold WSW. There are now cold air Cb's evident on the western and southern horizons.
The sat pic shows that the best of the cold air is still to the south, and should move over us, therefore the next 6 hours should be very interesting. The wind has shifted to the SW at the southern end of the bay and temps there are near 5 or 6.
I had 12.2mm to 9am.

(Jane ONeill - Bayswater - 11.15am Sat)
.5cm hail - no thunder. I often don't get hail because I'm right down in the valley of Dandenong Creek.
15mm rain to 7.30am
(Dane Newman - Kilsyth - 11.24am Sat)
Just had one rumble of thunder here and some small hail, temperature which was on 9C about half an hour ago has dropped back to 6C now (11.15am) 13.6mm of rain overnight takes the monthly total in Kilsyth to 22.0mm.

Looking SW to the heads

Looking SW from Beaumaris Yacht Club carpark - 12pm
(the snowline is at approximately 400 metres)
Photo - J ONeill (ASWA archive)

(Blair Trewin - Heidelberg - 1.03pm Sat) - hail also reported from Greensborough by Andrew McDonald
We've had two major bands of showers through in the last couple of hours, both with some hail. According to a friend at about 400m at Ferny Creek (Dandenongs) they are experiencing hail bordering on snow. There are radio reports of snow at Olinda (550m). Melbourne is currently at 7.6 C.

(Chris Maunder - Canberra - 1.53pm Sat)
I've also heard reports of snow at Ballarat.
(Jane ONeill - St Kilda - 1.58pm Sat - sitting in the car)
1.5 to 2m waves in the bay at 11.50am at Carrum
5 minutes worth of .5cm hail being blown almost horizontally, ending with 1 min of soft hail - hail lay on the ground for almost 10 minutes - waves coming over the sea wall in St Kilda Boat Harbour right across the road.
Temperature drop (this gives an idea of the origin of the downdraft) of 7.4C in 3 minutes!!

St Kilda Boat Harbour

Looking south from St Kilda Boat Harbour - 1.45pm
Photo - J ONeill (ASWA archive)

Looking south from St Kilda Boat Harbour - 2pm
Photo - J ONeill (ASWA archive)

(Lindsay Smail - Geelong - 4.23pm Sat)
Geelong's second coldest May day on record. (11 deg measured at BoM out of town) (Coldest was 9.5 on 27-5-87). My thermometer only made it to 10.3C at 2 pm. It was 6.9C at 11.30 am. Wind swung from SW to southerly at 10 am with some strong gusts. Urban area rainfall from 6 pm Fri to 4 pm Sat totalled 16.4 mm.
(Brisbane - 9.21pm Sat)
Some of the Melbournites in IRC were saying that there were two waterspouts sighted by spotters. Not surprising actually - At Geelong there was a 38kn low level jet at 850mb, 79kn at 700mb and 112kn at 500mb!!!!! Geelong's SRH was 473, and Melbourne's was 213! With the cold air aloft, I'm surprised there weren't any reports of any other vorticies - or, there may have well been, but just not reported. (SRH = Storm Relative Helicity, a value of over 450 is strong enough for an 'F4/F5')
(Rod Aikman - Bendigo - 10.03pm Sat)
Had a couple of showers about lunch time today with small winter 3-5mm dia. hail, but no thunder. The clouds looked rather glaciated near their bases, so had we had been a bit more elevated, snow could have reached the ground. Maximum temperature just 11.0C at 15:30 est. The frontal rain band reached here at about 03:00 this morning, but only resulted in 4.2mm of rain.
(Dane Newman - Kilsyth - 11.59pm Sat)
Official top temp in Melbourne today was 10.4C the coldest May day since 1977. Top here in Kilsyth was 9.3C. At 2.15pm it was just 4.6C here. Snow fell in many parts of the Dandenongs, Ballarat, Mt Macedon, Kinglake and no doubt several other low level locations. Most of the showers and hail has cleared now current temp (11.50pm) in Kilsyth is 4.4C.
(Rod Aikman - Bendigo - 2.41am Sunday)
To any of the Victorians on the list that may be interested in tracking the cold front across the state: From my barograph and thermograph traces, the cold front appears to have crossed Bendigo at 14:00 EST. Light to moderate rain commenced at 14:30 EST, and continued for just over 30 minutes, resulting in 4.0 mm. At 18:00 EST the screen temperature was 12.1C, falling steadily from the maximum of 20.5C at 14:00 EST. At 18:00 the wind was south, and the stratocumulus cloud was moving from the west. The rainfall from this front is fairly typical here for a non-interactive cold front at this time of year.

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Updated 22nd May 1999 - J ONeill