Microburst explained: Behind storm that smashed Brisbane suburbs

The cause of a 90km/h ‘microburst’ storm that smashed Brisbane suburbs on Thursday has been revealed – along with why meteorologists couldn’t issue a warning.

A tree was uprooted and smashed into a home on Gallipoli Rd at Camp Hill. Picture: Steve Pohlner

A microburst of wind was the culprit behind severe wind gusts and instantaneous storms in Brisbane’s southeast suburbs on Thursday, the Bureau of Meteorology has revealed.

Short but intense storms impacted Carina, Coorparoo, Morningside, Tingalpa, Seven Hills, and Carina Heights on Thursday afternoon, which downed powerlines and large trees across the area.

Major intersections were blocked off by police in Carina by 5pm, after large trees and branches collapsed onto powerlines.

Residents said the storm lasted just over ten minutes but left a trail of destruction across the area. SES had 40 call-outs from 2pm on Thursday until Friday morning, with just over half of them in Brisbane.

Residents survey the damage after the microburst storm hit suburbs in Brisbane’s east. Picture: Steve Pohlner

By 6am on Friday, more than 100 homes were still without power across Carina and Carindale.

The Bureau of Meteorology’s Dean Narramore explained that the area had experienced a dry “microburst” of intense wind gusts.

“Yesterday, we know it was very hot and humid but just above the surface. So we’re talking a kilometre, two kilometres above the ground,” the meteorologist said.

“There was some very, very dry air. So what happened was that thunderstorms formed. We’ll call high-based thunderstorms pretty high up in the atmosphere. Then, the rain underneath that small storm that went through the southern suburbs fell into this very dry air layer.

“We’ve got what we call evaporative cooling. So what it does is it rapidly cools the air around it and evaporates the rain. And as it does so, it also collapses, and that big cold brush of air kind of descends to the ground and then hits the ground almost instantaneously. It’s what we call a microburst.”

The Bureau of Meteorology said winds could have reached 90km/h. Picture: Steve Pohlner

Mr Narramore said the microburst, though not predicted by the weather bureau, likely saw winds of up to 90 kilometres an hour.

“It can be fine and sunny, and then the next minute you can get almost instantaneous bursts of 70, 80, or 90-kilometre winds, possibly even stronger,” he said.

“That is what caused all the damage and what we saw yesterday in a very localised area. It is what caused the storm around Carina Heights. It missed all our observations in the area but we did record a 76-kilometre wind gust in Archerfield.”

Another Bureau of Meteorology spokesman said the “rapidly changing nature of thunderstorms makes it difficult to forecast their exact location with long lead times”.

“Severe thunderstorms arise and move rapidly, which is why the Bureau supports targeted warnings with localised forecasts, briefings and public information in the hours and days leading up to an expected severe weather event.

“The Bureau provides the latest weather forecasts and warnings to help keep communities safe. We work closely with emergency management agencies and with government at all levels to provide expert insights, forecasts and warnings.”

Mr Narramore said microbursts were more common in inland areas of Queensland.

“We could easily see much higher wind gusts. This kind of event is more typical for inland Queensland – when you head out to Longreach, Winton and Mount Isa,” he said.

“They can regularly get these events where it’s 45 degrees and then a storm comes through. The storm collapses into that dry air and you get this big rush of wind which rips roofs off homes and downs power lines.”

Mr Narramore said that while another microburst was not likely for the area given the lower temperatures across the southeast, more showers were still possible.

“A couple of showers and possible storms again this afternoon, probably not as intense or high-end as what we saw yesterday in South East Queensland,” he said.

“But there still could be a couple of storms with heavy rain, and gusty winds.” 

Originally published as Microburst explained: Behind storm that smashed Brisbane suburbs