Rain, flash floods and thunderstorms sweep over Melbourne

Naaman Zhou
Photograph: David Crosling/AAP

Heavy rain, flash floods and severe thunderstorms have swept over Melbourne and rain is forecast to hit bushfire-affected parts of New South Wales and Victoria later this week.

In just 30 minutes, 44mm of rain fell at Avalon on Wednesday afternoon, and wind gusts reached 110km/h as wild weather hit the state’s south and moved north.

At St Albans, 54mm fell in 30 minutes between 4.15pm and 4.45pm as the bureau of meteorology updated its forecast to include the possibility of giant hail.

Across the country, the bureau has forecast up to 10mm of rain could fall over active fire regions in NSW and Victoria on Wednesday, with more expected on Thursday and Friday.

Related: Victoria faces more hazardous air as East Gippsland residents shelter on beach from bushfire

Up to 50mm of rain could fall across the NSW south coast from Wednesday to Saturday, and up to 25mm in the Snowy Valley and northern Victoria, where cross-border fires continue to burn through hundreds of thousands of hectares.

Earlier in the week, the NSW Rural Fire Service described the bureau’s rainfall projections as “all of our Christmas, birthday, engagement, anniversary, wedding and graduation presents rolled into one”.

Australia’s horror bushfire season has so far burnt through more than 10m hectares of land, killed 28 people, and destroyed thousands of homes nationwide.

On Wednesday, the bureau issued severe thunderstorm warnings for the Riverina and lower and upper western regions of NSW, and for Melbourne, Geelong and parts of the Mornington Peninsula in Victoria.

As of 4pm, multiple incidents of flash flooding had already been reported at Flemington, Pascoe Vale, Ringwood, Sunshine West and Altona North in Melbourne, and Lara and Portarlington near Geelong, according to VicEmergency.

On Tuesday, the bureau of meteorology also warned that the sudden heavy rain had the potential to cause damage – especially in fire-hit and burnt-out areas.

Bureau meteorologist Sarah Scully said on Tuesday the rain was “a bit of a double-edged sword”.

“Heavy rainfall and gusty thunderstorms bring the potential for flash flooding, particularly in the burnt-out areas of NSW and Victoria which are now vulnerable to landslips and trees coming down,” she said.

In Victoria’s East Gippsland, where the more than 160,000 hectare Border Fire continues to burn, up to 10mm of rain is expected on Thursday.

In Cabramurra in the NSW Snowy Valley, where the Dunns Road fire has combined with other fires and currently burns into Victoria, up to 15mm is forecast for Thursday. On the Victorian side, Corryong is forecast for the same amount.

Bateman’s Bay in NSW, which was hit earlier this month by 84,000 hectare Clyde Mountain Fire, can expect up to 15 mm on Thursday and 10mm on Friday. And Katoomba, near the Gospers Mountain megafire, is forecast for up to 20mm on Thursday and 20mm again on Friday.

On Wednesday, the bureau also issued severe thunderstorm warnings for Western Australia and Queensland. In WA, Gascoyne and parts of the Goldfields and South Interior regions were forecast for heavy rain and damaging winds, while in Queensland, giant hail was a possibility in the Central West.