SOMETHING incredible happened late Saturday night as the Antarctic Vortex unleashed its swirling fury on south-eastern Australia.

Thundersnow. Yes, thundersnow. It’s a very rare meteorological phenomenon, especially in Australia, where you mix all the elements of a tropical style thunderstorm with the bitter cold of a blizzard. It’s quite the climatic cocktail.

But that’s exactly what was on the menu as an aperitif to the main storm front in the Blue Mountains west of Sydney, as thunderstorms roared through the mountains accompanied by heavy snowfalls in the mountains themselves and in nearby towns like Orange.

Blue Mountains local and weather enthusiast Lindsay Pearce, who runs the site blackheathweather.com, captured the phenomenon from his verandah. You can watch it in the video at the top of this story. Nice work, Lindsay.

“Typically for NSW, we experience most of our thunderstorms in summer,” explains Mick Logan, a forecaster at the Bureau of Meteorology. “But thunderstorms can happen any time of the year if atmospheric conditions are right.

“Last night we had a series of strong fronts coming through, with really cold air at the mid levels of the atmosphere that allowed the line of thunderstorms to form.”

Thundersnow is so rare in Australia, especially outside the alpine regions, that the Weather Bureau keeps no data on its occurrence. And the Bureau keeps data on pretty much everything.

“For the Blue Mountains, it doesn’t happen every year,” Mick Logan says with a scientist’s typical understatement.

Best fall of snow we've seen since we've lived here #Orange pic.twitter.com/hMFhTXD6mN — Angela Barlow (@excelsior7) July 11, 2015

Mr Logan says the intense cold which has now engulfed the southern states will stick around for several days.

“The system has stalled a little bit, but there is more cold air to come through and there will be bands of moisture coming through for a couple of to come on and off.