BRISBANE, Australia -Floodwaters poured into the empty downtown of Australia’s third-largest city Wednesday after tearing a deadly path across the northeast, swamping neighborhoods in what could be Brisbane’s most devastating flood in a century.

The surging, muddy waters reached the tops of traffic lights in some parts of Brisbane and the city’s mayor said at least 20,000 homes were in danger of being inundated.

At least 22 people have died and more than 40 are missing across Australia’s northeastern state of Queensland since drenching rains that began in November sent swollen rivers spilling over their banks, flooding an area larger than France and Germany combined. Brisbane, the state capital with a population of 2 million, is the latest city to face down the waters, and officials expect the death toll to rise.

On Wednesday, Brisbane residents who had spent two days preparing took cover on higher ground while others scrambled to move their prized possessions to the top floors of their homes. Some stacked furniture on their roofs.

The Brisbane River is expected to reach its highest point on Thursday. After days of bad news in which figures were constantly being revised, the Bureau of Meteorology late Wednesday delivered a small and rare positive forecast – the floodwaters would crest about a foot lower than earlier thought.

If correct, the new forecast meant the waters would not reach the depth of the 1974 floods that swept the city. Queensland Premier Anna Bligh said the news was welcome, but of little comfort.

“This is still a major event, the city is much bigger, much more populated and has many parts under flood that didn’t even exist in 1974,” she said. “We are still looking at an event which will cripple parts of our city.”

The dragged-out crisis escalated when a violent storm sent a 26-foot, fast-moving torrent – described as an “inland instant tsunami” – crashing through the city of Toowoomba and smaller towns to the west of Brisbane on Monday. Twelve people were killed in that flash flood. Late Wednesday, Bligh said the number of missing had been revised down to 43.

“This is a truly dire set of circumstances,” Prime Minister Julia Gillard said.

The Brisbane River broke its banks on Tuesday and was continuing its rise Wednesday – partly controlled by a huge dam upstream that has had its floodgates opened because it is brimming after weeks of rain across the state.

Water levels were expected to stay at peak levels until at least Saturday, but many people won’t be able to access their homes for several days beyond that, Bligh said.

The flooding has transfixed Australia and is shaping up to become the nation’s most expensive disaster, with an estimated price tag of at least $5 billion. The relentless waters have shut down Queensland state’s crucial coal industry and ruined crops across vast swaths of farmland.

Brisbane’s office buildings stood empty Wednesday with the normally bustling central business district transformed into a watery ghost town. Most roads around the city were closed, and people moved about in kayaks, rowboats and even on surfboards. One of the city’s sports stadiums, which hosts international rugby games, was flooded with muddy, chest-deep water.

Boats torn from their moorings floated down the rising river along with massive amounts of debris. A popular waterside restaurant’s pontoon was swept away by the current and floated downstream. Officials said they would probably have to sink a barge that serves as an entertainment venue, to stop it from breaking free and becoming a floating torpedo.

Officials opened three more evacuation centers on Wednesday, and Newman said there was now room for 16,000 people to take shelter. Officials have urged people to get to higher ground and keep off the streets unless absolutely necessary.