Flash-Flood Warning As Week-Long Drenching Set To Soak East Coast

A deluge of rain has started falling in NSW and Queensland, but authorities are concerned heavier downpours in the north could trigger flash flooding.

A severe weather warning is in place for the northern rivers and mid north coast of NSW, with the Bureau of Meteorology issuing flood warnings for various parts of the state.

Inland regions including Bourke and Dubbo had received more than 20mm of rain by Thursday morning.

Major downpours have begun in Queensland, with Mount Elliot recording 140mm of rain already, according to BoM meteorologist Diana Eadie.

Communities near Tin Can Bay have copped the brunt of it, experiencing falls of about 300mm since 9am on Wednesday.

The state's southeast also copped a drenching overnight, with Brisbane's CBD under a severe storm warning after heavy rain caused commuter chaos with various roads blocked due to flash flooding.

BoM forecaster Kimba Wong says a band of heavy rain has swept from just south of Gladstone to the Sunshine Coast, with the deluge now affecting the capital and the Gold Coast.

Rain is battering Brisbane and surrounds. Image: BoM

And while many in bushfire or drought-affected areas are celebrating the welcome reprieve, Eadie said it will "bring its own risks".

The BoM has put numerous major flood warnings in place, including for areas such as the lower Flinders River, as well as flood warnings for Leichhardt, Cloncurry and Norman Rivers.

Heavy rainfall and storms are expected until early next week but it's still hard to determine exactly where the rain will fall.

"Rainfall will be hit and miss, but by the end of the weekend most areas through southern Queensland and eastern NSW will have been affected," Eadie said.

More than 50mm of rain is forecast for Sydney. Image: Google Weather

Eadie explained that the rain -- after giving Queensland a drenching -- will gradually make its way down the east coast.

The rainfall will start at the north and mid-north coast before shifting toward the Hunter Valley and into Sydney by the weekend.

There is also a final flood warning in place for the Burrum and Cherwell Rivers and a flood watch for coastal catchments south of Caboolture to the NSW border.

"The potential for heavy falls and flash flooding will continue to extend south during the week from south east Queensland to north east NSW," Eadie confirmed.



Drought-Stricken States Prepare For A Drenching, Possible Flash Floods

After suffering through a dry summer of fire storms and heatwaves, several states will experience heavy rain in the coming days.

She said "this is just one possible outcome" but we could also experience damaging winds and surf.

"This is an evolving situation."

Between now and Sunday rainfall totals of between 100mm to 200mm are possible for the east coast, but areas may see even heavier totals, according to Eadie.

Sadly the downfall is not thought to be enough to break the drought, with areas such as the Murray-Darling Basin so rain deficient that even this amount of rainfall will not make for significant inflows, a BoM spokesperson told ABC News.

The wet weather has also forced Cricket Australia to abandon Saturday's charity match for bushfire victims, which could now be moved to Melbourne.

Sydney is expected to see up to 50mm of rain on Saturday, forcing the league to consider other possible options.

However, they rejected calls to move the Big Bash league final to Melbourne despite the likelihood of a total wash out.

Over in Western Australia, communities on the coast of the Kimberly region are preparing for the first severe tropical cyclone crossing of the season.

The cyclone, to be named Damien, is predicted to bring torrential rain and wind gusts of up to 200km/ph.

BoM forecaster Andrea Peace said the cyclone is likely to track towards the Pilbara coast.

It could strengthen into a severe Category Three system before making landfall on Saturday. It is expected to cross the coast between Exmouth and Port Hedland.