Australia's south-east is about to shiver through a near-record late spring cold snap to start November, with Antarctic winds to bring unseasonal snow.
Temperatures through the week will drop as much as 15 degrees below average, cold enough for rare November snow along parts of the Great Dividing Range as far north as central New South Wales.
The last time it snowed in November that far north was 2008.
Following the state's wettest October on record, widespread storms could also trigger more flooding down the east coast.
Polar vortex weakening
The unseasonable chill is the result of a weakening of the polar vortex, which will allow very cold air to escape from Antarctica and move towards Australia this weekend.
That polar air will reach the South Australian coast on Monday morning, then sweep across the remainder of the south-east by Tuesday night.
The Antarctic blast will hit Victoria just in time for Melbourne Cup Day and conditions at Flemington will be cold and occasionally wet, with a wind chill close to only 5 degrees Celsius through much of the afternoon.
A second pulse of cold air should follow on Thursday, extending the spell of wintry weather through until at least Friday.
When and where will snow fall?
Snow will commence across the Alps on Monday night and, by Tuesday morning, should be falling below 1,000 metres on the Victorian ranges and across highland Tasmania.
Tuesday night should be even colder, and snow is likely to extend briefly north to the New South Wales central ranges, bringing snow to Oberon and, potentially, the higher cities of Orange and Lithgow, along with, possibly, the Blue Mountains.
Snow will continue across the Alps through Wednesday and Thursday, taking the event total snowfall to around 50 centimetres, a decent dump even for the middle of winter.
The polar air will also lead to thundery showers and small hail across parts of south-east Australia.
Cold blast to bring further flooding
The initial front will bring widespread showers and thunderstorms across central and eastern Australia from Sunday through to Tuesday.
This additional rain, following record October falls, will trigger renewed areas of flooding from southern Queensland down to Tasmania.
Major flooding is possible in pockets of inland New South Wales and Victoria but, thankfully, the severity is unlikely to match October's levels.
