Devastating flood photos as dams overflow in NSW, Victoria with rain forecast for Tasmania

The flooding emergency is far from over in Victoria, where there are 79 flood warnings in place.

A severe weather warning for heavy rainfall and snow is in place for parts of eastern Tasmania, with eight flood active alerts.

Floodwaters have torn across the rail networks leaving tracks damaged and passengers stranded.

The NSW SES received more than 900 requests for assistance and there were 222 flood rescues in the past 24 hours.

There are 120 warnings in place across the state, including 25 at emergency level.

Forbes is among the focus areas for SES crews as the Lachlan River rises above major flooding level, and the chance it may reach a record level of 10.8 metres on Tuesday afternoon.

Wyangala Dam has increased its flow to 230,000 megalitres daily which is spilling into the Lachlan River catchment.

"After 120mm of rain fell in the area on Sunday night, our members have worked alongside emergency service partners to prepare the Forbes community, including sandbagging and public information," NSW SES Deputy State Duty Commander Dallas Burnes said.

"We have as many emergency service resources as possible in the Central West, including rescue helicopters, the Australian Defence Force arriving today [Tuesday] and internationally-deployed personnel."

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NSW SES Commissioner Carlene York said the flood emergency in the Central West is the biggest flood response operation in NSW's history.

The SES has called on help from New Zealand, with the first 12 of 24 personnel from Fire and Rescue NZ now in Australia.

The firefighters are now in Parkes to support local NSW SES crews.

This is the first time the NSW SES has called for international assistance, and further support will arrive from Singapore and the United States later this week.

A beach on Victoria's Mornington Peninsula is closed after a landslip following heavy rains and flash flooding.

The SES has received 673 requests for assistance in the 24 hours to 5am, mostly at Mornington, Mt Martha and Safety Beach.

Showers and possible hail have been forecast south of the ranges from Tuesday, while isolated thunderstorms could hit northern Victoria before wild weather ramps up again from the weekend.

Multiple watch and act alerts have been issued across the state as the SES remains on alert.

A moderate flood warning has been issued for the Moorabool River at Batesford Bridge in Victoria's southwest, with water levels expected to reach four metres on Tuesday.

Meanwhile, the west coast of Tasmania has woken to a winter wonderland just weeks out from the start of summer.

Snow down to 400 metres is possible in the state's east coast and south east, with a road weather alert in place.

Heavy rain is predicted in the south east of the state, with flood advice alerts in place for a number of rivers including: Jordan, Huon, Coal, Macquarie, Break O'Day, South Esk and St Pauls.

- with Australian Associated Press