Supercell Saturday: Severe, high-energy storms forecast for weekend

Brisbane is in the firing line for the third consecutive weekend, with powerful “supercell” storms forecast for Saturday.

Brisbanites should not be deceived by Wednesday’s blue skies and balmy temperatures, said Bureau of Meteorology forecaster Shane Kennedy, with highly volatile conditions forecast over the next three days.

“We are looking at several unsettled, unstable days to come, with the real peak on Saturday,” Kennedy said.

More late storms could enhance the spooky atmosphere for Halloween on Friday night, but make it too wet and dangerous for trick-or-treaters to venture outside.

However, the most severe “supercell” storms are expected to roll in on Saturday, bringing the full suite of unpleasant accessories: gale-force winds, hail the size of golf balls (or larger), heavy rain and flash flooding.

“Yes, we could see some supercell, severe thunderstorms on Saturday,” Kennedy said, adding they could dump giant hail over the region.

Giant hail, he explained, is the kind that is five centimetres in diameter.

Residents could wake to plenty of sunshine on Saturday morning, Kennedy said, but they should not be lulled into a false sense of security.

“It will build up in the late morning and into the afternoon,” Kennedy said. “Most likely [the storms] will form inland and then travel towards the coast during the day.”

Conditions could ease a little on Sunday morning, before another round of thunderstorms rolls over the south-east in the afternoon.

“It’s looking pretty similar to the previous two weekends,” Kennedy said.

Last Sunday, Brisbane was thrashed by fierce afternoon storms that delivered large hail and heavy rain. Wind gusts up to 65km/h brought down hundreds of trees and powerlines, cutting power to 75,000 homes.

One house under renovation in Highgate Hill partially collapsed in the wild winds.

That was followed by a day of extreme heat, when the temperature reached 38.7 degrees – Brisbane’s hottest October day in 21 years.

Kennedy said a surface trough would move into the south-east on Saturday and combine with unstable, moist air to create ideal conditions for high-energy storms.

“It’s probably not clearing off until late next week,” he said.

Brisbane experienced its wettest day on Sunday since ex-tropical Cyclone Alfred drenched the city in March. The airport received 61 millimetres of rain, while 53.8 millimetres fell in the city.

So far this month, Brisbane has received 99.2 millimetres of rain, exceeding the monthly average of 85.8 millimetres.

That comes after Brisbane’s driest September in 38 years, with the city recording just 0.8 millimetres of rain.

This weekend’s severe storms could dump 50 millimetres of rain over parts of Brisbane, although widespread falls of 10 to 20 millimetres are predicted.

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