It was a treacherous but electrifying time to travel in South East Queensland (Qld) yesterday, as a dangerous thunderstorm passed through the region, dumping giant hailstones in its path.

Compared to the sunny morning at the state capitol, this storm seemed to come out of nowhere. But like all major storms, they have to come from somewhere.

Image: Evolution of yesterday’s storm in Brisbane

At 1:00 p.m. AEDT on the first day of November, a cloud that had formed on the NSW side of the state border began to rain a light downpour on the Queensland town of Killarney. Little did he know that it would become a weather spectacle watched by thousands of people.

Around 1:30 p.m. AEDT, the eastward-moving cloud developed into a storm with all the characteristics of a continued increase in intensity: the atmosphere was relatively moist at the surface to feed the storm with moisture; it was warm enough to keep the storm active; and the upper atmosphere seemed ideal to help any storm that developed continue.

Image: Satellite image at 12:00 AEDT showing the location of the start of the storm (yellow circle), relative to the dry, warm surface air of inland New South Wales and Queensland, and to moist and mild surface air along the coast.

At 1:46 p.m. AEDT, the Bureau of Meteorology issued a severe thunderstorm warning for north-east New South Wales, followed by another warning for Qld at 2:00 p.m. AEST (meaning the warnings were issued more than an hour apart). Why these two warnings at different times? Winds around the storm had torn it in two, moving one south into New South Wales and the other north into Queensland, leading to a severe thunderstorm warning for Queensland. These types of storms are called split supercells, and in the Southern Hemisphere, the split cell that moves to the left of the “split zone” (in this case it would be the one that moves north) tends to become stronger than its sister in the southern hemisphere. RIGHT.

And that’s exactly what we saw yesterday. The storm in Queensland made a B-line to Brisbane, reaching the state capital in two hours and growing into a formidable supercell during that time (as seen in @Cal_Spencer’s X post).

The storm is brewing #Brisbane right away pic.twitter.com/sh3llrfvDK

– Cal Spencer-Rosenberg (@Cal_Spencer) November 1, 2024

It caused approximately 34,000 lightning strikes during its lifetime, heavy rain and giant hail. Brisbane recorded 9mm of rain in 10 minutes between 3:50pm and 4pm AEST, and residents reported hail of all shapes and sizes reaching the size of a tennis ball. But that’s not all. Strong wind gusts from the storm created a spinning vortex over the Brisbane River, which looked like a tornado to onlookers:

Twister on the Brisbane River!!! ????️

From what I can tell, this is not a full-fledged tornado, but rather a “burst” which is a more transient feature on the leading edge of the storm.

It looked like there were still strong winds!

Credit: Hayden Oakley pic.twitter.com/SD6V8GoU5T

-Tony Auden (@TonyAuden) November 1, 2024

The storm eventually headed offshore into Moreton Bay at 4:30 p.m. AEST, dissipating at 5:20 p.m. AEST on the northern shore of Moreton Island.