The worst is yet to come for an already soggy Sydney, as drizzle from a cold front moving across the state on Tuesday develops into a downpour within days.
A separate weather pattern brewing off the east coast is expected to lash the coastal regions of NSW as it moves from the state’s northeast to the southeast over several days from Thursday.
The rain bomb could also drench the southeast corner of Queensland at the beginning of its southern journey, and the northeast of Victoria as the trough develops into the weekend.
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“We’re going to see this low-pressure trough deepen through the northeast of NSW,” Bureau of Meteorology spokesperson Belinda House told 7NEWS.com.au.
That trough will bring wet onshore winds from the east, with the potential to generate widespread showers.
First to be affected is the Northwest Slopes and Plains, right across to the Tablelands and through the Northern Rivers.
Up to 50mm of rainfall is likely on Thursday, House said.
The weather system could also lash the already-soggy southeast of Queensland as it deepens on Thursday, House said.
Rain will ease up in these areas, with a chance of drizzle remaining into the weekend as the rain bomb moves further south.
“By the time we move into Friday, we’re going to see that risk of significant rainfall heading right down the east coast of NSW,” House said.
The rain band will extend into Sydney, the Hunter region, the Blue Mountains and the Illawarra on Friday.
Up to 80mm of rainfall is likely in these regions on Friday, House said.
By Saturday, it will be the Illawarra and the southeast copping the brunt of the wet weather.
Up to 50mm of rainfall is expected in the affected areas on Saturday.
But the Bureau is uncertain how the weather pattern will develop from Friday onward.
“We’re going to have to wait to see exactly how it develops and exactly where it shifts,” House said.
Over the state’s southern border, Victoria has already been battered by wild weather, with warnings in place as flash-flooding caused road closures in Melbourne overnight.
The downpour led to terrifying scenes in the state’s Great Dividing Range, when a woman fell into a flooded stormwater drain in Daylesford, and was carried away in fast-flowing water up to her neck.
In Queensland, flash-flooding also stranded dozens of campers near Mount Isa over the weekend.