Forecasters say they are concerned for suburbs along the Hawkesbury-Nepean River as Sydney's Warragamba Dam is predicted to spill later on Saturday afternoon as record-breaking floods wreak havoc along the NSW coast.
The spill may combine with the overflow of other rivers, like the Upper Nepean river and also the Grose River.
“Based on our current modelling, we're thinking that we might see some minor flooding at Penrith and North Richmond during later today and then depending how the rainfall events unfold, we might see moderate flooding develop later today and overnight," the Bureau of Meteorology's Justin Robinson said on Saturday.
When asked if there were any suburbs in particular that forecasters were worried about, Mr Robinson said: "I guess we're concerned about all of the suburbs that lie along that river, but I guess we're all concerned about Penrith and Windsor and the communities which can get deep levels of flooding."
Mr Robinson said the current forecast looked similar to the extreme weather event experienced in February 2020, which had "significant impacts" on the North Richmond and Windsor communities.
The lower Blue Mountains region is expected to get about 200mm to 300mm of rain.
Record-breaking rainfall in Mid North Coast
"It's a very significant, record-breaking event with the rainfall that we have seen," BoM's Agata Imielska said, adding the rain seen in the Mid North Coast and Hunter regions breaks other March records by 100 to 200mm.
Kendall, on the Mid North Coast, has already recorded 450mm of rain and Kindee Bridge has seen 160mm in just three hours.
"It's not just the total rainfall amount, it's also how quickly and intensely that rainfall has actually fallen," Ms Imielska said.
BoM experts say the NSW Mid North Coast is "not out of the shadows" yet, even though rain has eased. More heavy rain in flooded communities is possible on Saturday night, Ms Imielska said.
The trough that's flooded parts of the Mid North Coast is now moving south and affecting greater Sydney, with the lower Blue Mountains expected to see the worst of the rain in the next 12 to 24 hours.
"For the Greater Sydney region, we are looking at rainfall totals, widespread across the region of around 100mm," Ms Imielska said.
Moderate to minor flooding is possible for Greater Sydney but that will depend on exactly where further rain falls.
More to come.
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