Thunderstorms, giant hail and powerful winds forecast for NSW as wild weather hits east coast

Dangerous and severe “supercell” thunderstorms with the potential for giant hail and destructive winds were forecast for parts of New South Wales on Sunday, as volatile weather continued in the eastern states over the weekend.

Storms dumped heavy rain across large parts of northern and eastern NSW and much of Queensland on Saturday, with strong winds recorded up to 98km/h in Goulburn and rainfall totals of between 30mm and 50mm in the Coffs Harbour area.

A man in his 20s was struck by lightning while swimming at Ettalong beach on NSW’s Central Coast on Saturday afternoon. He was pulled from the water by fellow swimmers and given CPR by first responders until NSW Ambulance paramedics arrived. He was taken to Gosford hospital in a serious condition, and later transferred to Royal North Shore hospital.

The young man was in a critical but stable condition on Sunday morning, a hospital spokesperson said.

Witnesses said while there was storm activity visible in the distance towards Gosford, the area around the beach was clear and sunny and that the lightning bolt appeared to come “out of nowhere”.

Lightning can strike up to 30km from the centre of a storm cell.

Sunday was expected to be “another big storm day”, with “very dangerous and severe thunderstorms” likely for north-eastern NSW, said Sarah Scully, senior meteorologist at the Bureau of Meteorology.

Those storms could bring hail with a diameter greater than 5cm, and winds in excess of 120km/h.

“That’s being driven by a southerly change that’s pushing up the New South Wales coast,” Scully said. “It’s a potential trigger for these supercell high-end thunderstorms.”

Severe thunderstorms with 2cm hail, wind gusts in excess of 90km/h, heavy rainfall and flash flooding was possible on Sunday through a broader area of NSW extending down towards inland parts of the ranges to the east of Sydney, and pushing up into south-east and central parts of Queensland.

Storms were expected in Sydney on Sunday, but were likely to be less severe than further north, though rain was likely. The forecast temperature was 23C. Showers and thunderstorms were expected in Brisbane with a top of 31C.

The BoM expected to release more severe weather warnings throughout Sunday as the storms develop.

On Monday, the risk of high-end severe thunderstorms would move into the NSW northern rivers and south-eastern parts of Queensland, including Brisbane, the Gold Coast and the Sunshine Coast, again with the potential to bring giant hail, destructive winds, and intense rain that could lead to life-threatening flash flooding.

“That again is being driven by that trough that’s pushing up the coast combined with the very humid conditions that eastern Australia has been experiencing the last few days,” Scully said.

A coastal trough with a low-pressure system appeared to be developing off the north coast of NSW near the Queensland border, which had the potential to bring even more rain onto the coast.

“How much rainfall accumulates is highly dependent on how close that trough sits to the coast, and also how long it lingers there,” Scully said.

“At this state we’re only expecting moderate rainfall totals during tomorrow from that coastal trough, between 30mm to 70mm, easing into Tuesday morning. But we are watching it very closely as rainfall totals associated with these coastal troughs are notoriously challenging to predict. If they just move that little bit closer to the coast they can sometimes dump a whole lot of rain.”

Elsewhere, there were showers developing in Melbourne on Sunday with a forecast top of 17C. There was a high chance of showers in Hobart, with 13C expected, and cloudy in Adelaide with a mild 20C forecast. It was partly cloudy in Canberra, where they were expecting 24C, and in Perth, with an expected top of 28C. Darwin was expecting 34C and an afternoon storm.