NSW hit by flash flooding and intense rainfall as Queensland on cyclone watch

<span>Photograph: Melanie Russell/AAP</span>
Photograph: Melanie Russell/AAP

New South Wales emergency services have carried out 42 flood rescues, including the evacuation of a nursing home, after intense rainfall caused flash flooding Wednesday night into Thursday afternoon.

The NSW SES have responded to more than 600 calls for help across the south coast, Illawarra and metropolitan Sydney areas, including many rescued from their cars, as of Thursday afternoon.

The SES said the Illawarra region was the hardest hit, with over 350 incidents and 21 rescues from flood water recorded since midnight.

Southern zone deputy commander, Sharon Fox, said a number of schools and roads have had to be closed across much of the Illawarra and south coast due to the weather, which was still dynamic and hazardous.

A Culburra aged care home in the Shoalhaven needed assistance evacuating some residents at 1.45am Thursday morning due to flooding and major roof leaking, requiring water to be pumped out of it.

A family also had to be evacuated overnight when their home flooded at Culburra Beach, where 100mm of rain fell within an hour.

Related: Norfolk Island residents warned as tropical cyclone Gabrielle forms off Queensland coast

NSW SES State duty commander, Colin Malone, said the intense rainfall was expected to continue for into this evening.

“The weather system we’re monitoring has the potential to move into the metropolitan parts of Sydney and could be problematic during peak hour traffic,” Malone said.

Jonathan How, a senior meteorologist at the Bureau of Meteorology, said there was intense rainfall on Wednesday night into Thursday morning south of Sydney airport towards the Illawarra and south coast.

Greenwell Point north of Jarvis Bay received 379mm within 24 hours, including 178mm in two hours.

How said there were rainfall totals above 100mm towards Wollongong while southern suburbs of Sydney including Marrickville, Little Bay, the airport, Sans Souci, and Peakhurst picked up more than 50mm.

“A real contributing factor has been how warm the sea surface temperatures have been off NSW … above 26 to 27 degrees off Sydney and Illawarra,” How said.

High sea surface temperatures caused the recent humid conditions in Sydney and made more moisture available for showers and storms, he said.

The storms were “very much confined to the coast”, according to How. For example, Nowra – only 10km inland from Greenwell Point – only received 10mm of rain.

In Queensland, Tropical Cyclone Gabrielle is expected to intensify over the Coral Sea as it moves south-east. How said on Thursday morning the cyclone was quite far offshore – 600km from Mackay.

“There is no direct threat of any landfall and we are not expecting any rainfall because the system is just so far away off the coast,” How said. “But we will see Gabrielle track pretty close to or almost directly over Norfolk Island on Friday night.”

There was no direct threat to Queensland or NSW, though the cyclone was producing some large waves and strong to gale-force winds.

A hazardous surf warning was issued in Queensland and NSW, from south of Capricornia down towards the mid-north coast of NSW.

How said the cyclone could reach a category two system on Thursday and potentially a severe category three by Friday, which would mean offshore wind gusts of up to 224kmh.

Across the country, How said summer temperatures were returning to South Australia with 36C predicted for Adelaide on Thursday and heat pushing into Victoria on Friday.

Heatwave conditions will develop across north-east NSW and south-east Queensland over the weekend, How said.