'Monitor conditions': Millions on alert for major soaking, storm

A new safety alert has been issued for Sydney this morning as the SES warned of torrential rainfall.

The warning urged people in greater Sydney, the Illawarra, and the Central Tablelands to "monitor conditions and follow safety advice - particularly residents in (the) Sydney, Wollondilly/Wingecarribee and Greater Wollongong areas".

Stay up to date with the latest warnings on the Bureau of Meteorology website.

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The new warning comes after the SES previously alerted New South Wales to widespread flash flooding potential around the state.

Areas threatened include metropolitan Sydney, the Illawarra, and parts of the state's north and north-east.

"Flash flooding is dangerous and unpredictable. It can occur suddenly and without warning," the SES said in a post on X.

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The Bureau of Meteorology's Dean Narramore yesterday forecast "severe thunderstorms" today through eastern NSW and southern Queensland.

"It's going to see widespread rain and thunderstorms through much of eastern New South Wales on Friday afternoon into Friday evening," he said.

Heavy falls have already been recorded this morning as BoM issued severe thunderstorm warnings for Sydney, the Blue Mountains, the Hawkesbury, the Illawarra, the Hunter, and the Central Tablelands.

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"The Bureau of Meteorology warns that, at 8.25am, severe thunderstorms likely to produce heavy rainfall that may lead to flash flooding were detected near Oakdale and Warragamba," one warning read.

"They are forecast to affect the area west of Picton by 8.40am and Camden, Picton and the Nattai Tablelands by 8.55am."

Falls of 74.5mm were observed in just two hours this morning at Kangy Angy on the Central Coast, and 70mm in three hours at Lake Macquarie.

People are urged to keep clear of creeks and storm drains, not ride or drive through floodwaters, and contact Triple Zero in emergencies.

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