The heaviest downpours of up to 200mm will hit the South Coast and Illawarra, prompting widespread flash flood warnings.
Sydney's Warragamba dam - already at 99 per cent capacity - is forecast to spill, bringing a flood threat to those downstream.
Severe Weather Update 10 May 2024: Heavy rain forecast for southern — Bureau of Meteorology, Australia (@BOM_au) #NSW coast this weekend. Video current: 2pm AEST 10 May 2024.Latest forecasts and warnings: https://t.co/4W35o8iFmh or the BOM Weather app. pic.twitter.com/gmddWfsv1yMay 10, 2024 Heavy rain forecast for southern NSW coast
The water reservoir last spilled after heavy rain in April, causing catastrophic damage to some homes near the catchment area.
The Bureau of Meteorology's Sarah Scully said some coastal areas could receive anywhere between 50 and 100mm of rain on Friday night.
Some inland areas could be hit with isolated totals of between 50 and 70mm with thunderstorms predicted to increase the rate of rainfall and the risk of road closure.
⛈️NSW weather on Sat 11/5: Deepening coastal trough will bring heavy rain to SE NSW, incl. — Bureau of Meteorology, New South Wales (@BOM_NSW) #Illawarra #Shoalhaven #SouthCoast during the weekend, increasing risk of flash flooding. Any storms in the area & #Sydney Coast will bring heavier falls. Warning https://t.co/EIDIQ98q7d pic.twitter.com/3vCbkWM3y5May 10, 2024
However, the really heavy rainfall won't start until Saturday, with the rainband moving across to southeast NSW.
The potential for severe thunderstorms in the Sydney Metropolitan area and Illawarra will increase the risk of flash flooding.
Further south, rainfall totals of between 70 and 100mm are likely with the potential for up to 200mm in 24 hours.
Stay prepared and stay safe this weekend ☔— NSW SES (@NSWSES) Severe weather with heavy rainfall is predicted within inland Western NSW and in the #Illawarra and South Illawarra, down to the #Shoalhaven.Monitor warnings via the our website https://t.co/ntTR3jP6ts or via the #HazardsNearMe app. pic.twitter.com/MYCrDfs7EXMay 10, 2024 NSW SES warns wet weekend ahead
The NSW State Emergency Service said heavy rainfall could cause the Hawkesbury River to flood, with isolated minor flooding in parts of the Hawkesbury Nepean Valley including North Richmond and surrounds.
A severe weather warning for heavy rainfall could also lead to flash flooding across northern parts of the South Coast, southern parts of the Illawarra and eastern parts of the Southern Tablelands from Saturday morning and into Sunday.
Wet weather is also forecast for neighbouring parts of Queensland and Victoria.
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