There is no sign of any let up in the downpours that have left towns isolated and forced evacuations in central-southern Queensland – with NSW now in the firing line.

The Bureau of Meteorology issued a severe weather warning for inland southern areas of Queensland, including the Channel Country, Maranoa and Warrego districts, on Friday.

Up to 100 millimetres more rain was expected, with isolated rainfall forecast to cause further flash and river flooding.

There are flood warnings – meaning existing or expected flooding– for multiple rivers, including Cooper Creek and the Bulloo, Paroo, Thomson, Warrego and Barcoo.

Heavy overnight downpours also triggered flooding at the Mary River near Gympie on Friday.

“There is a lot of water still flowing into these inland catchments and this flooding is likely to continue for quite an extended period of time,” meteorologist Jonathan How said.

A major flood warning was also current for the Pioneer River near Mackay, with more flood warnings for the Ross, Bohle and Haughton Rivers near Townsville.

Heavy rain is set to move south-east later on Friday and into the weekend, bringing deluges and possible flooding as far south as northern and eastern NSW.

The weather bureau issued a severe weather warning across north-western NSW on Friday. Areas likely to be affected included Narrabri, Walgett, Cobar, Bourke, Lightning Ridge and Brewarrina.

“A trough and upper disturbance that brought widespread heavy rainfall to parts of inland Queensland will dip southwards into northern inland parts of the state today, before tracking into eastern districts over the weekend,” it said.

Moderate to heavy rainfall, which may lead to flash flooding, may develop about parts of the Upper Western this morning, extending to the northern reaches of the Central West Slopes and Plains and adjacent districts this afternoon.

“Six-hourly rainfall totals between 30-50 millimetres are likely, with isolated falls of up to 75 millimetres possible. 24-hourly rainfall totals of between 50-100 millimetres are likely, with isolated totals of up to 130 millimetres possible.”

For inland hotel owner Koss Siwers the torrential rain means the reopening date for his outback business.

Siwers would usually have already made the 10-hour drive to Adavale from his other residence in Brisbane to reopen the remote hotel, which he runs from March to October.

But the arrival in south-east Queensland of ex-tropical cyclone Alfred’s arrival in earlier in March meant a dramatic change of plan.

Weeks later, Siwers was again ready to hit the road – until he saw pictures sent online by his Adavale neighbours. There was water up to the hotel’s floorboards – and it was still rising.

Adavale, which is nearly 1000 kilometres west of Brisbane, was evacuated on Thursday after hundreds of millimetres of rain left only one high-set house standing clear of floodwaters.

“Here I was in Brisbane and then this bloody cyclone came, so I thought ‘geez I better stay’ because I was a bit concerned about the property and the neighbours,” Siwers said.

“I was just about ready to go on Saturday, now this flooding has happened in a flash – it’s bloody unbelievable.”

The pictures of an inundated Adavale were sent to Siwers before the outback town’s entire population of about 30 was evacuated.

It follows downpours of up to 400 millimetres that have triggered widespread flooding across Queensland’s central and south-west.

The wet weather has cut roads, isolated communities and disrupted telecommunications across inland Queensland.

At Quilpie, about 100 kilometres north of Adavale, there has been about 500 millimetres of rain in a week – its normal yearly average.

“I will have to wait for the water to go down. Usually, it takes about a week,” Siwers said of his Adavale Pub plans.

“I was packing up ready to go back with stock, ready to open the pub again.

“Now it looks like all the wet has moved out west.”

Queensland Premier David Crisafulli said the government’s attention would turn to affected primary producers when the flooding and rain subsided.

“There’ll be significant livestock loss,” he told ABC TV on Friday.

“You’re dealing with hundreds of thousands of acres that is underwater and significant loss which has a big economic flows through the communities.”

-with AAP