A large storm lasting about 15 minutes swept over Brisbane following a short period of high humidity bringing lighting and high winds but no hail.

A DAMAGING storm has turned "day into night'' in Brisbane, as lightning and winds brought down powerlines and left more than 6000 homes and businesses without electricity.

Meanwhile, another severe thunderstorm warning has been issued for other parts of the state.

The Queensland State Emergency Service was busy cleaning up the Brisbane CBD this afternoon after wild weather ripped through the city around 11am today.

In Ipswich, a small grass fire was sparked when lightning struck a crane next to the city's hospital just after 10am but the incoming rain extinguished it, a Department of Community Services spokeswoman told AAP.

In Ann Street in the CBD, a hotel roof collapsed under the storm while another 72 calls for assistance were made asking for help with leaking roofs and fallen trees,

"It turned day into night,'' a SES worker said.

"It came quickly and then it left.''

A weather alert was posted by the Bureau of Meteorology just minutes before rain smacked the east coast, leaving thousands of people without power.

Weatherzone reported more than 4000 lightning strikes within 80km of Brisbane in the space of one hour.

A police spokesman said 50 people were evacuated from an inner-city building after the storm caused a partial cave-in of the roof of a lodge in the inner suburb of Wilston. He said the storm had also caused a minor fire in Seventeen Mile Rocks, in Brisbane's south-west, after a house was struck by lightning.

For full coverage of the storm go to www.couriermail.com.au

Police also reported they fallen trees across roads in Milton, Kangaroo Point and the Fortitude Valley area.

People in Brisbane, Redlands, North Stradbroke and parts of the Gold Coast. Logan and Moreton Bay have been badly hit with thousands of homes left without power, falshing flooding and partial road closures.

An Energex spokeswoman said many homes and businesses had been left without power, particularly on Brisbane's southside.

"It's widespread at the moment. We can see there are about 6000 or 7000 homes and businesses around our network without power," she said.

Supercell thunderstorms with the potential to create tornadoes are threatening to smash NSW and Queensland this weekend.

Considered the most dangerous storms, supercells develop where wind shear is present through a very unstable atmosphere.

"Supercell thunderstorms are likely to produce severe weather," said Tom Saunders, Senior Meteorologist at The Weather Channel.

He said such extreme weather events were "likely across northeast New South Wales and southeast Queensland this weekend and have the potential to cause flash flooding, damaging winds and large hail".

"The wind shear leads to rotation within the storm and a longer lifespan," he said.

"Supercells often cause very heavy rain and flash flooding, large hail, damaging winds gusts and occasionally tornadoes.

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The more intense thunderstorms this weekend have the potential to bring around 50mm of rain, but most of northeast New South Wales and southeast Queensland are expected to receive at least 20mm. Weather Bureau senior forecaster Jonty Hall said thunderstorms were expected to develop in west Queensland about midday and move towards the coast in the afternoon.

"With the warm humid conditions and the help of an upper level trough, that’s going to lead to reasonably unstable conditions as well," he said.

"The threat increases from early afternoon onwards to early evening."

Storms have already struck in parts of Queensland, with Pittsworth Newsagency employee Lauren O'Shea reporting a storm hit the location just after 8.30am.

"There was a fair bit of rain and thunder and lightning," she said.

Storms are likely right into northern NSW and have the potential to produce about 50mm of rain.

In Queensland, any storms will follow an early burst of hot weather.

Ipswich is expected to record a top of 37C on Saturday, as will Brisbane's western and southern suburbs.

Much of the west will be in the 40s.

Weather Bureau forecaster Bryan Rolstone said the hottest place in the state would most likely be Bedourie in the far southwest, with 43C.

"A northwest wind will bring hot air out of the Gulf (of Carpentaria) and the NT," Mr Rolstone said.

"There'll be more moisture around on Saturday and a trough will be right on us, providing lift and moisture.

"We're about a month behind with our storm season, but moisture levels are rising."

with wires