Sydney deluge, flash floods a 'one in 500-year' event

Sydney is set for another splash of rain today, as flood warnings persist — but the heavy deluge that drenched the city on the weekend will weaken after record-breaking falls.

Falls of 80mm to 140mm were recorded in "one to three hours" on Sydney's Northern Beaches and the Central Coast, Weatherzone reported yesterday.

The weather reporting site said these were comparable to tropical monsoon falls and consituted "one in 200-to-500-year events".

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Flash flooding occured in parts of Sydney and flood warnings remain current today, including for the Hawkesbury and Nepean rivers in the city's west.

"This intense rainfall was caused by a deep feed of moist easterly winds coming off the very warm Tasman Sea, directed over the region by a coastal trough," Weatherzone said on Sunday.

"Over 19,000 lightning strikes have also been recorded within 100km of Sydney since midnight on Friday, most of which were over the northern suburbs and Central Coast areas."

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That trough is set to move away from the coast today, though some showers are forecast for Sydney throughout the day.

After that, the week is set to remain mostly dry for the city, aside for the chance of some heavier rain on Friday.

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Currently, a severe weather warning for heavy rain is in place for Norfolk Island, with forecasts of more than 60mm in one hour or 120mm in six hours.

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