Much of southern Australia can expect more storms and renewed flooding as a fresh wave of dangerous weather crosses the country in coming days.

In Victoria, heavy rain is forecast to bring rapid river rises, flash flooding and put more pressure on full catchments, while NSW and other states can also expect dangerous weather conditions between Friday and Monday.

“A dangerously unstable atmosphere will produce an outbreak of severe thunderstorms over several states in southern and eastern Australia this weekend, with supercells a good chance and tornadoes also possible,” forecaster Weatherzone wrote on Friday.

“All of the ingredients will be in place for dangerous thunderstorms in parts of southern and eastern Australia this weekend.”

Weatherzone forecaster Anthony Sharwood went further.

“There is one seriously long band of precipitation extending the best part of 2000 kilometres, and it’s just a sign of what’s to come for the eastern half of the country over the next few days,” he said.

Weatherzone’s rain model for the coming days. Image: Weatherzone

Weatherzone said storms were possible across the entire country in the next three days, with parts of SA, NSW, Victoria and Queensland most likely in the firing line.

“The combination of rain and intense thunderstorm downpours could also exacerbate flooding across parts of Queensland, NSW, Victoria, SA and Tasmania this weekend and early next week,” Weatherzone wrote.

In Victoria, widespread showers and storms on Sunday are expected to bring moderate to major flooding across parts of the state’s north-east, which are expected to receive 60-90 millimetres of rain.

Heavy rain and large hail pose a threat to the rest of the state, while parts of Melbourne and Riverine communities could also experience flash flooding.

On Friday afternoon, the Bureau of Meteorology issued a severe thunderstorm warning for parts of outer northern and eastern Melbourne. It followed extreme thunderstorm asthma conditions and a tornaod warning in Victoria’s west on Thursday.

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A flood watch has been issued for more than 25 rivers and 45 warnings remain active.

Communities most at risk include Benalla, Wangaratta, Wodonga, Yarrawonga, Tocumwal and Shepparton.

It is feared water could rise to about the same level as the devastating 1975 floods in low-lying areas along the Murray, such as Mildura, Robinvale, Boundary Bend and Wakool Junction.

The NSW SES said it was preparing – and asking the community to do the same – for flooding to rise to new heights in inland NSW this weekend. Commissioner Carlene York said some evacuation orders might need to be reissued in coming days.

“With the saturated catchments, the wet ground, [and] the full rivers, we are very concerned about the rainfall that is forecast over the next few days impacting some of the areas that we have seen some severe flooding,” she said.

“We are looking at some areas of concern, which is Forbes and Condobolin, and we are anticipating that there will be a chance of heavy rain around that area.”

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Victoria’s Hume Dam is already at 96 per cent capacity, prompting authorities to release 95 gigalitres per day.

Murray-Darling Basin Authority executive Andrew Reynolds said the operation was a delicate balancing act between freeing up space for future rainfall while minimising the impact on communities downstream.

Victoria SES chief operations officer Tim Wiebusch said almost every water storage facility in Victoria was at capacity and flooding could continue for another six to eight weeks.

“We can’t emphasise enough that this flooding emergency is continuing, people need to remain alert to their conditions,” Mr Wiebusch said.

Below-average temperatures are expected to set in next week, creating snow in Alpine areas.

There have been about 14,000 calls for help to the Victorian SES since the disaster began about a month ago.

About 150 people and pets affected by flooding are living at Melbourne’s Mickleham Quarantine Facility.

-with AAP