Evacuation sirens have been sounded in the Lockyer Valley town of Grantham and residents there are being told to leave immediately after 80mm of rain in the catchment on Thursday morning. One swift water rescue has been conducted in the town.

Premier Annastacia Palaszczuk, Queensland Police and the Bureau of Meteorology all issued serious warnings about approaching storms and the danger of more lives being lost as the dangerous front lingers over the State.

Police Commissioner Katarina Carroll said the situation was now “extraordinarily serious, dangerous and life threatening”.

Ms Palaszczuk said the BOM had provided an update that more bad weather is on its way.

“There are severe conditions that are going to be experienced over the north of Brisbane, northern Moreton Bay region, Fraser Coast, Sunshine Coast, Gympie, Wide Bay all the way to Bundaberg,” Palaszczuk said.

“This is of serious concern so what we are asking people to do who live in these regions … you should collect your children (from school) when it is safe to do so.

“We are warning people that this is a serious situation. It is extremely unstable weather conditions and as a precaution we would like people to collect their children when they think it is safe to do so. They are safe at school until they can go and collect them.”

And Palaszczuk urged everyone in the region to listen and watch the reports from the BOM and local councils.

“Today is the day to be listening … the conditions are going to be unstable for the next 24-48 hours.

“These are unprecedented times.”

Palaszczuk urged people to stay off the roads and for those involved in flood clean up activities to get a tetanus shot.

The BOM has advised that the conditions will continue through Thursday and for the next 48 hours.

“This is a very dangerous and potentially life-threatening situation for south east Queensland and it is continuing today and potentially for the next 48 hours with active and potentially severe storms,” BOM meteorologist Laura Boekel said.

She said creeks would rise quickly given the saturation of the ground.

Some areas of the State were inundated with more heavy falls overnight. In Brisbane city, 48 mm fell in just 30 minutes and at Maroochydore 52mm fell in 30 minutes. Hail of five to six centimetres fell in Inglewood at midnight and Dalby airport has recorded wind gusts of 93km per hour.

At 10.45am, the Queensland Fire and Emergency Services issued an emergency alert for the flood hit Lockyer Valley town of Grantham.

QFES said the Lockyer Valley Regional Council had advised flash flooding was possible and residents were urged to move to safe areas away from the town.

The tiny town was washed away in the 2011 floods and a week ago was again inundated by a torrent of water.

The Sunshine Coast is also under a flash flooding alert.

Hail measuring up to six centimetres hit towns in the Sunshine Coast hinterland in the early hours of Thursday.

Brisbane’s CBD was hit with a dangerous storm at about 7am, bringing wind gusts of about 90kmh, soaking commuters and causing more traffic chaos as the city tries to clean up from the weekend’s deluge.

The storms have followed the worst floods in a decade, which have killed nine people and damaged more than 17,000 homes and businesses.

Transport Minister Mark Bailey said the ferocious storms have knocked trees across the Sunshine Coast’s main train line between Caboolture and Nambour and a number of roads with about 37,000 properties without power.

“I’m in the CBD at the moment and it’s just torrential, it looks like a cyclone out there,” he told ABC Radio on Thursday.

“So it’s a pretty cruel and tough day for everyone out there who are recovering from from having their houses flooded.”

Six centimetre hail pummelled Windera, north of Brisbane, while stones from 5-6cm smashed into the southern town of Inglewood on Wednesday night and the early hours of Thursday morning.

Mr Bailey said the train system has been only partially online, and there had been plans to gradually reopen more roads, but people should stay home on Thursday due to the risk of flash flooding.

“The rain that we feared is happening, and … if you don’t need to go out, please don’t, stay off the roads, and that’s the key thing at the moment,” Mr Bailey said.

Police are still searching for an elderly man who fell from a boat into the swollen Brisbane River near Breakfast Creek on Saturday afternoon.

Brisbane City Council had been gearing up to mobilise more than 10,000 in the Mud Army 2.0 to clean up the city after it was swamped with floodwaters this week.

However, Lord Mayor Adrian Schrinner said the new storms have put clean up and recovery efforts on hold.

“The BoM advice is pretty sketchy on this, I think it’s sort of said 30 to 80 millimetres yesterday and then up to 150 mm,” he told ABC Radio.

“So, you know, we’re not sure what we’re dealing with, but hopefully it’s a short, sharp downpour and then we can get back to the clean up efforts.”

Cr Schrinner said unlike 2011 floods, which mainly impacted areas near the Brisbane River, combined river and flash flooding in creeks has caused damage in every one of Brisbane’s 190 suburbs.

“So every suburb has creeks running through it, every suburb had localised flooding, and there’s impacts in every suburb and you just see that right across,” he said.

Giant hail around 5 to 6cm was recorded just west of Inglewood around 12:10am, while Woodford recorded 66 mm of rain in 30 minutes before 3am.

Meanwhile, authorities have re-floated a 150 tonne crane in the Brisbane River that had come loose from its moorings at the height of the weekend deluge.

Police were concerned the crane could smash into the Howard Smith Wharves or damage the Story or Gateway Bridges.  However, it was secured on Monday and a pair of tugboats were observed taking it downriver on Thursday morning.

-with AAP