Heavy rain to 'wreak havoc' across eastern Australia for several days

Despite a relatively dry weekend, eastern Australia — including flood-stricken parts of Victoria and New South Wales — will once again be smashed with heavy rainfall and storms this week.

Another low pressure system and trough "in what seems to be a never-ending conveyor belt" is expected to "wreak havoc" across the country, according to meteorologists at Weatherzone.

The system will intensify and push across the Northern Territory and South Australia on Tuesday before settling over Victoria, NSW, Queensland and Tasmania for "several days".

"Widespread rain and storms will likely renew and cause more riverine flooding as soil moisture reaches its limits," Weatherzone said, adding that any further precipitation is "likely to run straight into river catchments and increase the chances of flooding".

While 20 to 40mm of rainfall is anticipated, some areas already struggling to recover from recent flooding could see 100 to 150mm by Friday.

"While rainfall amounts might change in the lead up to this event, widespread rainfall is likely, and it won't take a large amount to see rivers rise again," Weatherzone said.

The heavy rainfall will linger for days due to a high pressure system that is feeding moisture back into the system, it added.

"This is commonly referred to as a blocking high, which as the name suggest blocks the typical west-to-east motion of weather systems, causing events to slow down and last several days," Weatherzone said.

NSW residents urged to flee

Ahead of the grim storm system forecast for later this week, NSW residents living in already saturated catchment areas could see some showers develop on Sunday night, the Bureau of Meteorology says.

However, inland areas that have received the bulk of recent rainfall are expected to be spared a further deluge.

Residents in parts of Narrandera, on the Murrumbidgee River in the Riverina region, have been told to leave due to moderate flooding, warned they may become isolated if they remain beyond 6pm on Sunday.

The river's main flood peak has passed Wagga Wagga but further downstream is expected to deliver moderate flooding at Darlington Point from Thursday, and has passed the minor flood level at Balranald.

Major flooding from the Murrumbidgee River is not expected to reach the town of Hay until late October, the BOM says.

People in tourist and caravan parks at Moama, on the Victorian border, have been told to evacuate by 9am Monday.

Major flood warnings are in place for 11 rivers in NSW.

Major flooding at Warren is expected to continue and more rain could cause further rises on the Macquarie River, threatening more severe flooding at Wellington and Narromine in the coming days.

Troops called in to help flood-hit Victoria

Heavy downpours in Victoria — which is grappling with widespread flooding and evacuations in the state’s north — are expected to affect towns along the Murray River, including in Moama from midweek.

On Sunday, the Australian Defence Force was called in to help flood-affected residents as the crisis worsened. About 100 ADF personnel are on their way to help with evacuations and sandbagging in the worst-hit areas.

There were 146 flood rescues in the past 24 hours, with the majority in the Shepparton area, the Victorian State Emergency Service said.

Shepparton has been hit by major flooding, with the swollen Goulburn River expected to continue to rise through Sunday before peaking at 12.2 metres early on Monday.

That was higher than the 1974 flood level of 12.09m, the Bureau of Meteorology said.

Major flooding has peaked at Murchison, where the Goulburn peaked at 12m. It has also hit communities along the Avoca River to Charlton, where the rising waterway had swollen to 7.73m on Sunday morning.

The river at Charlton could peak at 8am on Monday.

More than 350 roads are estimated to remain closed in flood-affected areas and about 6000 properties are without power.

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Premier Daniel Andrews says some families will not the able to return to their homes for "extended periods of time" as the Commonwealth prepares to reopen a Covid-19 quarantine facility for displaced residents.

He said the crisis was unlike any other flooding event because high rainfall had left catchment areas sodden and more rain was forecast.

"These (river) peaks, even once they recede off the high mark, there will still be water in the communities and houses will remain uninhabitable for extended periods of time," he said.

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