South-east Queensland has received a "scary" amount of rain, with more than 400 millimetres falling in less than 24 hours near Gympie.
More rain is on the way with the Bureau of Meteorology (BOM) warning the Sunshine Coast and nearby hinterland could get more than 200mm on Wednesday and Brisbane another 100mm.
The body of a 60-year-old woman was found at 8am in a submerged car at Belli Park, west of Eumundi in the northern Sunshine Coast.
Police are also searching for a 54-year-old man whose motorcycle was found in floodwater at Cedar Pocket, north-west of Noosa, at about 7:30am.
Police Superintendent Craig Hawkins said people should make preparations for road closures and power disruptions.
"If there's no need to be out on the road, then I encourage people not to be there," he said.
The highest rainfall so far has been recorded at Mt Wolvi, near Gympie, where 425mm fell in the 24 hours to 9am on Wednesday. Nearby Beenham Valley Road got 419mm and Kin Kin got 355mm.
An emergency alert has been issued for flash flooding in the region.
Senior BOM meteorologist Laura Boekel said some parts of south-east Queensland are "likely" to receive more rainfall in this one event than they usually do for all of February.
"Some areas might see up to a metre of rain from this event as an accumulated total over the next few days, which is a significant amount of rainfall for south-east Queensland," Ms Boekel said.
However, she said it is difficult to pinpoint the exact locations that will experience these high rates of rainfall.
About 140mm fell in just one hour on parts of the Sunshine Coast hinterland overnight and BOM forecaster James Thompson said about 300mm had fallen in just six hours in the national parks, east of Gympie.
"Hopefully there weren't too many people in that area because [there was a] pretty scary amount of water falling from the sky and potential flash flooding," he said.
Closer to the capital, 50mm fell at the airport overnight and 97mm at Mount Cotton.
There were more than 100 requests to the State Emergency Service for help from flooded properties, mostly in the Sunshine Coast, Gympie and Noosa regions.
Swift water rescue teams were called to 27 incidents overnight.
A dozen of those were from people trapped in floodwaters near Gympie.
A couple was plucked from a tree after their caravan and car were washed away at Mothar Mountain, south-east of Gympie, in the early hours of this morning.
Emergency services also attended a freight train derailment at Traveston about 3:20am, where the train was knocked from its tracks by flooding.
Ms Palaszczuk said the driver sustained minor injuries.
Due to the derailment and weather, Sunshine Coast line trains were suspended between Caboolture and Gympie North stations.
Trains between Springfield Central and Central, and Darra stations were also cancelled on Wednesday morning.
The Ferny Grove train line in Brisbane has also been temporarily affected by damage to overhead powerlines.
Flooding has closed seven schools on the Sunshine Coast, Noosa and Gympie regions.
Dams spilling over with more rain on the way
Ms Palaszczuk said 15 dams were at capacity with several spilling, including Baroon Pocket Dam on the Sunshine Coast, Hinze Dam on the Gold Coast and Leslie Harrison Dam in the Redlands.
"Locally intense rainfall is possible and since many catchments are now saturated there is an increased risk of dangerous and life-threatening flash flooding over the coming days," she said.
A severe weather warning has been issued for areas between Maryborough to the Gold Coast and stretching west to Toowoomba.
Ms Boekel said south-east Queensland can generally expect 100-200mm of rainfall and more intense pockets of activity could exceed 300mm.
"We are encouraging people to keep updated with the warnings, and especially the radar, to see where the really intense rainfall is going to fall so they can be prepared if it does come to them," she said.
Ms Boekel said the Stanley River to Woodford is currently under a flood warning, which is the river system that flows to the Brisbane River catchment.
"Currently we have the Brisbane River in the watch area," she said.
"So we really are trying to give the early heads-up to people in the Brisbane River catchment area that we could see more rainfall and what we see in Brisbane will depend on the bullseye of that rainfall."
Ms Boekel said the flood season typically peaks in March, meaning falls around the Brisbane River over the next few days could be a sign of more to come.
"While some catchments like Sunshine Coast and Mary River are already saturated and they are responding really quickly to any rainfall, further south, where the river catchments haven't had as much rainfall in the past few months, this could be more of a priming event.
"Catchments could respond slowly and we could see more rainfall for the rest of the season."
Queensland Fire and Rescue state coordinator James Haig said multiple crews across the state were standing by and ready to face the expected deluges across south-east Queensland in the coming days.
Locals sleep in cars, 'stuck for days'
Summa Court, from Federal on the Sunshine Coast, said it was a scary night and there would be lots of cleaning up.
"We slept in the four-wheel-drive my five-year-old, myself and hubby and dog," she said.
"We are flooded in for at least a couple of days.
"Hopefully we don't get large amounts of rain in a short time.
"We have lived here for five years, but this is the highest I have ever seen the creek come up. It was higher than Cyclone Debbie."
Owner of the Kin Kin General store Jodie Williams is trapped at her farmstay and does not know how her horses and cattle have fared.
"The heavy, heavy, heavy rains — I could tell by 2.30 this morning. I could see that the property was flooding. There wasn't a lot of notice, not a lot people could do. The water was moving very fast across the road," she said.
"I can see that the flood water is across the flats. I would say it's a metre deep.
Wayne Voss from Pomona said his property had received 400mm overnight and his backyard had disappeared.
"We haven't slept. We're mopping up underneath the house," he said.
"You've got no idea and I don't think the rest of town has fared that well either."
