Storms cells tracking across eastern Australia are likely to bring further stress to many already inundated regional areas in New South Wales and Victoria, agencies warn.
A weather system is bringing renewed thunderstorms, heavy showers and likely river rises to inland NSW on Monday, which is a concern to the NSW State Emergency Service, says an assistant commissioner, Nicole Hogan.
“We understand this is the last thing you want to hear, with flooding affecting multiple communities in inland NSW,” she said.
The Lachlan River was rising at Forbes in the state’s central west on Sunday after experiencing a historic flood a week ago, while a major peak was also occurring downstream at Condobolin, she said.
The SES was continuing to support the Forbes community as it recovered from the inundation, she said.
The commissioner, Carlene York, urged people to follow warnings and evacuation orders.
“Some people are still not listening but they make, regretfully, their decisions based on what they’ve seen in the past,” York said.
Sign up for Guardian Australia’s free morning and afternoon email newsletters for your daily news roundup
“But we’ve seen time and time again the water is rising further than perhaps what it has for many years and that’s because of the saturation of the land.”
A cold front was expected to sweep across NSW on Sunday and continue into Monday, bringing storms and adverse weather.
Snow is expected in the Alps and central tablelands.
The SES has delivered supplies of food, medicine and animal feed to 1,000 residents cut off by flood waters since severe weather began in mid-September, and carried out 500 flood rescues.
The volunteer workforce was fatigued and personnel had been requested from other states, York said.
Flooding continues across western and southern NSW, in towns including Collarenebri, Walgett, Bourke, Condobolin, Hay and Albury.
To the east, some 61mm of rain fell on the northern rivers town of Grafton in just one hour on Saturday night, leading to flash flooding and five requests for SES help.
Severe storms with a possible flash flooding risk were forecast across eastern Victoria on Sunday, with intense showers forecast at Seymour, Wodonga, Wangaratta, Corryong, Bright, Mansfield, Falls Creek, Mount Hotham and Mount Buller.
Major flooding is continuing at Echuca, Moama, Torrumbarry and Barham along the Murray River.
While the Bureau of Meteorology expects heavy rainfall to ease across much of Victoria on Monday morning, the Murray River is not expected to recede later this week.
A severe storm on Saturday left some 163,000 South Australians without electricity, with about two-thirds remaining without power on Sunday afternoon.
More than 423,000 lightning strikes were recorded, with heavy winds downing trees and SA Power Networks receiving more than 500 reports of fallen wires.
“SA Power Networks has mobilised all possible resources and has called in interstate field resources to assist,” said a spokesperson, Paul Roberts.
Some customers would remain without power until Tuesday, he said, and further delays were possible, as crews worked to repair damaged infrastructure.