Blizzards and hazardous swells have hit much of Australia’s southeast as the Bureau of Meteorology issued surf and wind warnings for several states on Monday.
Coastlines along the south-east have been hammered by heavy swells and an Antarctic blast brought winds with speeds up to 150km/h in Tasmania. These winds cut off power to 20,000 homes across the state. More than 3500 properties were still without electricity on Monday.
Police have warned people not to climb Hobart’s kunanyi/Mt Wellington summit after another hiker had to be rescued late Sunday. Eight people were rescued from the summit over the weekend and the wild weather also claimed the life of a woman who was killed by a falling tree.
Alerts were issued across New South Wales, Victoria and Tasmania for high seas battering southern-facing coastlines.
On the west coast severe warnings have been issued for the southern coastal areas of Western Australia between Esperance and Albany for 70km/h winds with gusts of 100km/h.
BOM meteorologist, Jackson Browne, said the cold was brought by a slow moving high pressure system created by winds launching off the Antarctic coast and hitting Australia the next day.
“Instead of winds travelling west to east as they normally do in the mid latitudes, we saw a lot of north-south movement,” Browne said. “Looking back at some of the satellite imagery, you can see where the Antarctic sea ice begins off the coast and these winds were sitting near the edge.”
“These winds really rocketed across the Southern Ocean on to Tasmania.”
Snow fell down to 400m as operators at Ben Lomond, Tasmania’s largest ski field, scrambled to open early and take advantage of the situation.
Netty Maree Elms from Ben Lomond Ski Lifts said it was her first season on the slopes and that waking up to snow was “absolutely beautiful”.
“What I’ve heard people say is this is some of the best snow they’ve seen here for years, for a long, long time,” Elms said. “People are super excited and just happy to be up here, with some snow to ski and snowboard in.”
“Last year the season only lasted three weeks and got rained out in August, but this year I think people are hoping it will hang around a bit longer and they will be able to enjoy it a bit more.”
Weather forecasts have been careful to manage expectations about future snowfalls.
“If I was a betting man, I wouldn’t be holding my breath for persistent snow cover this winter,” Browne said. “There’s no guarantee it’s here to stay.”
Browne said predicting snowfall in Australia was “vexed” as the country’s weather systems were determined by what occurs in the Indian and Pacific Oceans. As both bodies of water are currently quite warm, they were likely to produce a “warm, wet winter” for southeastern Australia.
The weather system also brought with it high speed winds that “whipped up” the ocean, leading to waves up to nine metres high off Hobart.
Browne said this “southerly shove of energy” is now moving northwards into Gippsland with areas such as Mallacoota expected to experience high seas on Monday, with concerns about coastal erosion on southern-facing New South Wales beaches.
Angus Gordon, a coastal engineer said although the weather system was producing waves with lots of energy, NSW beaches were unlikely to be hit hard.
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Water reached the seawall at Collaroy and there had been some spectacular breaking waves at the south-facing Bondi, however conditions were not right for erosion to occur.
“In the years where we’ve seen fairly massive erosion, we find you’ve got a low pressure system in the Tasman Sea, rather than being swell south,” Gordon said.
“These low pressure systems elevate the water level. For every millibar of pressure, there’s a one metre rise in sea level.”
Gordon said coastal erosion was more likely to occur along southern Australian coast in regions like Inverloch or Tasmania’s west coast, but people should still be cautious on NSW beaches like Collaroy, especially where water is travelling far up the beach.
“Collaroy survives for now. Yet the fact the water gets right up to the wall should be of concern, as it means last night it was not safe to walk along it,” Gordon said. “Any time the waves are washing around your feet, and you can’t easily get out, you shouldn’t really be there.”
“You’re going to get the occasional big set of waves come through that will take you out. And it doesn’t take very much to knock people over.”
Conditions were expected to ease as this wave energy dissipates into the Coral Sea.
However Lord Howe and Norfolk Islands were currently “being whalloped” by swells of seven to nine metres, and the west coast of New Zealand is bracing for waves of eight to 10 metres.
Browne said that while it was not unusual to see waves up to six metres in the Southern Ocean during winter, 10m waves reaching New Zealand and nine metre waves in Hobart accompanied by high wind speeds “was pretty extraordinary”.
Though it is not possible to attribute any single weather event to global heating Browne said over time it would lead to more energetic weather systems
“For every integer of warming we have 7% more moisture in the atmosphere,” Browne said. “We’re seeing more energetic weather systems because we’re adding more energy into weather systems.”