Rare snowfalls are forecast this week for communities outside south-eastern Australia's mountainous regions when a blast of wintry weather sweeps in.From tonight into early tomorrow, a polar air mass will generate snow on the mountains of Victoria, Tasmania, NSW and the ACT, reports weather channel Weatherzone.But, unusually for late autumn, elevated areas below the mountains can also expect dumpings.LIVE UPDATES: Fresh Trump threat to IranThe polar air mass is due to sweep into south-eastern states overnight.