A dramatic change in the weather pattern is set to bring widespread rain to Australia's east coast this week, following last week's intense heatwave and destructive bushfires.
The shift will deliver a "sustained period of wet weather" according to the Bureau of Meteorology (BoM), which will help ease the immediate bushfire danger, but also raises the risk of flash flooding.
More than 700 structures have been destroyed or significantly damaged in the Victorian fires, including 228 homes and 450 outbuildings.
Meanwhile, the remnants of ex-Tropical Cyclone Koji continue to produce heavy rainfall across tropical Queensland, while a separate tropical system is expected to develop over the Top End this weekend, bringing renewed flood concerns and a possible cyclone.
Severe storms and flooding rain for NSW and Victoria
Eastern NSW and Victoria are bracing for their most significant rainfall in months, as storm activity intensifies from Thursday.
Thunderstorms with heavy rainfall and a heightened risk of flash flooding are likely across Queensland, NSW, Victoria and the ACT, centred over East Gippsland, the south-east corner of NSW, and areas along the state's northern slopes and ranges.
By Friday, the main thunderstorm zone is forecast to concentrate over central eastern and north-eastern NSW, while steadier rain and isolated storms develop along the NSW south coast and across Gippsland.
Weather models indicate the heaviest rainfall band, accompanied by gusty winds, will gradually shift northwards along the coast during the weekend.
By Sunday, the focus is expected to be on the Illawarra, Sydney basin and the Hunter region, where flash flooding remains a concern.
While flash flooding is possible across several districts, there is also a river flooding risk in the Illawarra and south coast.
The BoM reports that catchments are relatively dry, increasing the chance of minor flooding.
Ex-Tropical cyclone creating wet conditions
Flooding rain is also forecast across parts of northern Australia as ex-Tropical Cyclone Koji continues to drift north-west across Queensland.
Koji's remnants are expected to trigger further localised heavy falls and flash flooding from the Gulf Country to the Central Coast on Thursday, with thunderstorm downpours continuing on Friday.
The BoM forecasts more than 100mm of rain over north-east Queensland and western parts of the NT in the coming week.
Flood watches remain in place for 15 rivers and creeks across the Gulf Country, western and central Queensland, and Cape York.
The chances of Koji redeveloping into a cyclone remain low, at 15 per cent or less until at least next Wednesday, the BoM reports.
As conditions ease in Queensland, a new tropical low is expected to form off the Top End.
BoM forecasting models suggest the system may drift west offshore early next week, bringing a 25 per cent chance of cyclone development off the north coast of Western Australia next week.
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