Why do supercell thunderstorms form and what makes them so dangerous?
More than 80,000 households were left without power after south-east Queensland thunderstorms downed more than 400 powerlines.
Residents in parts of south-east Queensland are adding up the damage toll after an intense supercell thunderstorm ploughed a path of destruction across Brisbane's south earlier this week.
More than 80,000 households were left without power — the vast majority in the Logan area — after the thunderstorms uprooted trees, tore roofs off houses and downed more than 400 powerlines.
More than 24 hours later there were still tens of thousands of homes without power.
Senior meteorologist David Crock said Wednesday's weather was a "classic spring thunderstorm outbreak" for south-east Queensland.
The storm that eventually hit Logan had formed south of the border and tracked north before forming into a supercell thunderstorm.
Supercell thunderstorms can live much longer because of how they move, Mr Crock said.
"They get a bit of extra strength and they start rotating. It's similar to the sort of physics that makes a cricket ball swing."
"That separates the updraft of the thunderstorm where it's taking in that moist, humid, warm air from the downdraft of the thunderstorm which is where the rain is falling and the wind's coming down through the storm."
Generally once a downdraft descends, the thunderstorm "chokes" and dies out.
But in a supercell thunderstorm, once the updraft and the downdraft are separated, the storm can "keep firing" longer than an average thunderstorm, and reach much greater intensities.
Supercell thunderstorms can produce damaging and destructive wind gusts, heavy rainfall, large to giant hail and even tornadoes.
Mr Crock said there is always an "element of luck" as to where a supercell will hit and which suburbs bear the full impact of the storm.
South-east Queensland is a hotspot for supercell storms, with the Scenic Rim corridor from Toowoomba down to Tambourine a "sweet spot" for the formation of dangerous storms, Mr Crock said.
"Everything lines up there more often because they've got that added help from the topography from the hills as well as that rich moisture," he said.
Storm cells that head towards Brisbane from the south-west can often have "all the ingredients" needed to create a supercell thunderstorm, he added.
"Not every time, but sometimes all the factors are lining up," he said.
The SES has a checklist of things you can do when storms are forecast.
- thunderstorm
- form
- household
- power
- south
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- queensland
- powerline
