Mr McDowell said the Hunter region is likely to see some severe thunderstorms, and heavy rain and large hailstones cannot be ruled out, but it depends on where the storms develop and how they move.
He said a cold front will move through on Friday night or Saturday morning and “things will cool off quite dramatically”, with weekend maximum temperatures of 20 and 22 degrees forecast in Sydney.
In the state’s south, the bureau has issued a severe weather warning for widespread damaging winds averaging 60 to 70 km/h, with peak gusts of up to 100 km/h, for people in the Illawarra, South Coast and Snowy Mountains districts, and parts of the Southern Tablelands, South West Slopes and ACT.
Nowra, Thredbo, Bowral, Batemans Bay, Eden, Goulburn and Cooma may be affected, it said.
“An intensifying low-pressure system over western Victoria is expected to track east-southeastwards towards the eastern Bass Strait this morning,” the bureau said on Friday. “In response, vigorous northwest to westerly flow will develop over southeastern New South Wales.”
Mr McDowell said these “mountain waves” form when strong winds run over the mountains and a wave-like feature brings some of those strong winds down to the surface.
People across the state are encouraged to keep an eye on the Bureau of Meteorology warnings.
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