Warnings of huge supercell storm with massive hail to hit Sydney this afternoon 

Rain, hail and enormous thunderstorms are predicted to sweep across the east coast of Australia and hit Sydney and Melbourne by Monday afternoon.

Large hail stones, damaging winds and much-needed heavy rainfall are expected to hit swathes of southern NSW.

A severe thunderstorm warning has been issued for the southwest slopes and nearby regions.

The Bureau of Meteorology on Monday morning said severe thunderstorms were likely to form from north of Newcastle to the NSW-Victoria border on the coast.

A severe thunderstorm warning was also issued for the southwest slopes, as well as parts of the southern tablelands, central-west slopes and plains, Riverina, lower western and Snowy Mountains regions.

Areas likely to be hit by heavy storms included Wagga Wagga, Albury, West Wyalong, Griffith, Narrandera and bushfire-affected Tumbarumba.

BoM said the low-pressure system prompting the thunderstorm warning would move east to the Tasman Sea by Monday night.

Winds will shift and come more from the north and west mid-week, bringing drier and warmer air – and higher fire danger – on Wednesday and Thursday.

But rain will return on Friday and the weekend.

Meanwhile in Victoria, the town of Broadford recorded 50mm of rainfall in 45 minutes overnight.

Bushfire-ravaged parts of Victoria now face the possibility of flash flooding as the state prepares for its wettest two-day period in months.

Heavy rain, damaging winds and large hail are possible in eastern parts of the state including East Gippsland where fires continue to burn.

A severe weather warning was put in place on Sunday at 6pm for heavy rainfall expected to develop across the state on Monday.

‘Widespread falls of 10-30mm are forecast for the warning area, with isolated falls of 60-80mm associated with thunderstorm activity’, the warning read.

Across other parts of the state, widespread falls of 20-50mm are forecast with peak falls to 100mm possible. Much of the rainfall is expected to pour in periods of 4 to 6 hours.

‘We’re going to see some potential flash flooding and severe thunderstorms over the next couple of days, including some damaged fire areas,’ Emergency Services Minister Lisa Neville warned.

‘Victoria is about to see its wettest two-day period in many, many months,’ Bureau of Meteorology senior forecaster Dean Narramore added.

While rain was welcome in the state, it did come with dangers.

‘Unfortunately coming in this massive amount in one go, quickly does cause some risk … both in how you capture most of that … and also debris run-off and the potential for fallen trees,’ the emergency services minister said.

More to come.