Cold fronts bringing snow to the southeast highlands
A pair of vigorous cold fronts are currently lashing parts of Australia's southeast, and alongside damaging wind gusts, snow is falling over the highest areas of Tasmania and Victoria, with New South Wales not far off.
Severe weather conditions are impacting many parts of South Australia, Tasmania, Victoria and southern New South Wales as the strongest cold fronts in a while unleash powerful winds and a sharp reduction in temperatures. As a result, snow has started falling over some alpine areas. Places like Ben Lomond in Tasmania and Victoria's Mt Baw Baw are currently seeing snow flurries. The Snowy Mountains of New South Wales will likely start to see some flurries later today as the fronts push further northeast.
The snow will be relatively light, and it will mainly be rain and showers over the mountains. However, a good few centimetres should be on the ground until the cold fronts move off over the Tasman Sea. This time of year, the ground is still too warm to maintain snow so it will melt over the weekend and early next week.
Still, for those wanting winter to finally arrive so they can jump on their skis and snowboards this is a welcome sight. Looking ahead to what kind of winter we should expect over the resorts, we first look to what the climate drivers are doing. At this time of year we switch our attention from the El Nino-Southern Oscillation (ENSO) to the Indian Ocean Dipole (IOD), which becomes active as the monsoon trough migrates north. Currently, the IOD is forecast to be in a neutral state for most of the winter, which means there is no increased chance of greater or lesser than average rainfall. A negative IOD may form towards the end of winter, which brings increased moisture to the southeast, and if temperatures are cold enough, we see more snow.
A lot of the snowfall depends on how close the lows and fronts are to southern Australia, as opposed to being closer to Antarctica. The Southern Annular Mode (SAM) is the north-south movement of the westerly wind belt in middle to high latitudes. Lows embedded in the wind belt are what brings us snow in winter over the mountains. Just like the IOD, a negative SAM - meaning the wind belt is migrating north - is good for snow. So the best combination is a negative IOD and a negative SAM.
The SAM moves north and south pretty regularly, so if your trip can be flexible, keep an eye an the forecast for negative phases, that's your best bet for a good dump.
© Weatherzone 2018