More dangerous weather is hampering the search for a family of seven missing in flood-stricken remote Western Australia.

The missing group, which includes three elderly people and four children, has not been seen since leaving Kalgoorlie-Boulder for the remote Aboriginal community of Tjuntjuntjara, 650 kilometres away, on Sunday.

WA Police said on Wednesday they were unable to launch land or air searches as severe weather and floods continued to batter the region.

Hundreds of millimetres of rain have soaked a huge section of WA, in what some pastoralists are calling a “once in a lifetime” flood. More rain was forecast for Wednesday, before easing later in the day.

“Due to severe weather conditions this morning, we have not been able to deploy any air assets in relation to the search for seven people who were travelling from Boulder area to the Tjuntjuntjara Aboriginal Community,” a WA Police spokeswoman said early on Wednesday.

“As soon as the weather improves, an air asset will be deployed.

“At this time, road conditions are dangerous, particularly in relation to the route we believe the people have taken.

“Motorists travelling in the Goldfields area are urged to check the Main Roads and Bureau of Meteorology sites for current information on road conditions.”

WA remains cut off from the rest of Australia after the Trans-Australian Railway line, a key freight route running between it and South Australia through the Nullarbor, was closed on Sunday when floodwaters inundated parts of the track. The Eyre Highway is also closed.

It follows six months of rain in the region in just 24 hours, leaving much of the Nullabor under water.

Australia’s largest sheep station, Rawlinna, is also under water after receiving 155 millimetres of rain – more than half of its annual total – since 9am on Friday. The station covers an area roughly equivalent to the Sydney metropolitan area 400 kilometres east of Kalgoorlie.

“OK, we said we’d never turn away the rain but it’s starting to get very wet out here!” the station posted on Facebook on Monday.

“There’s water through the cookhouse, the workshop and spare parts room! The gennie shed is flooded and there’s water in the petrol tanks… and more on the way.”

On Tuesday, the station confirmed all its workers were “safe and dry” with only a handful of staff remaining on site.

“The homestead is almost completely under water but it’s also worth mentioning that it’s built on the edge of a depression/donga so the water was bound to pool there (we just never imagined we’d get this much!!),” they wrote.

“The paddocks are likely very wet too but Rawlinna sheep are not silly and we are hopeful they’ve all found high ground. As soon as we can get back in the air we’ll be out there to check on them.”

Grave concerns for missing family

Strongest fears remain for the missing family, who police said were believed to be carrying minimal food in their two vehicles.

Western Australia Police Inspector Mick Kelly said he had been told one vehicle had water, bedding and camping gear.

The group – two elderly drivers, an older woman and four children aged seven-17 – were meant to arrive at their destination on Monday morning.

“We’re praying that they’ve stayed with the car,” Kelly said on Tuesday.

The group is reported to be travelling in a beige Toyota LandCruiser, registration No.A683, and a white Mitsubishi Triton, registration No.KBC8881.

The missing family are believed to be driving in these two vehicles. Pictures: WA Police

Kelly said the plane looking for them could stay in the air only for an hour on Tuesday.

“But our pilots are the experts and quite simply, while we want to have every opportunity to bring these people back to the community safely. We can’t afford obviously to put those that are out there looking and searching in danger,” he said.

Meanwhile, WA’s Department of Fire and Emergency Services said severe weather warnings remained current as a “near-stationary trough” was forecast to produce a “band of heavy rainfall” in the area.

Isolated six-hourly rainfall totals of 30-80 millimetres were possible, DFES said.

“A separate severe thunderstorm warning will be issued if very dangerous thunderstorms with intense rainfall are detected,” DFES said.

“Locally intense rainfall, which may lead to dangerous and life-threatening flash flooding, is also possible with embedded thunderstorm activity in the Eucla district.

“Heavy to locally Intense rainfall is forecast to ease below warning thresholds this afternoon or evening.

“People in Eucla and Rawlinna in Eucla district need to take action now as minor flooding is expected over the coming days.”