The clouds parted above Medicine Hat, Alta., on Sunday, while local residents pumped out waterlogged homes and braced for another wave of heavy rains and possible flooding.

The city, which has already experienced extensive flooding due to recent precipitation, may be hit by another 40-50 millimetres of rain by Monday morning, said Police Chief Andy McGrogan.

"We're anticipating more of the same type of problems," he said.

Officials declared a state of emergency on Saturday and about 600 people have been told they should leave their homes. McGrogan said the evacuation notices were not mandatory but 44 families had sought refuge in emergency shelters. The notices likely won't be lifted for some time, he added.

"Right now the things are stable and that's great, the sun's shining," McGrogan said. "Obviously the concern is what's going to happen with the rain."

The low-lying land of Medicine Hat is normally arid, making flooding unusual. But torrential rains across Alberta and Saskatchewan in the past few days has damaged homes and shut highways. As much as 150 millimetres of rain has drenched the region.

Jack Clark said he tried to carry out as many valuables as he could from the house of his neighbour, who was out of town as flood waters rushed into her home.

"It was running in the side door," he said. "It sounded like Niagara falls ... Unreal."

Leila Daoud, with The Red Cross, urged residents affected by the evacuation notices to register with the organization and leave their homes voluntarily, "while they can still take some basic items with them."

In Maple Creek, Sask., floodwaters crested Friday, overflowing the banks of the town's namesake creek and sending a deluge into many people's homes. At least 80 households were evacuated, along with patients of the town's hospital, as virtually the entire community was submerged.

Despite the evacuations, Maple Creek Mayor Barry Rudd said no one slept in his town's emergency centre.

"Because it's a small community," Rudd told CTV News Channel on Saturday, "everybody went to someone else's place to stay."

Rudd expects the cleanup to take its toll on his town, but said the economic impact would be felt most by those who use the nearby Trans-Canada Highway.

Floodwaters caused a large sinkhole to form in the westbound lane of the highway near Maple Creek, stopping traffic on the region's most important highway. It isn't known when the road will re-open.

"There is no access to get through to Medicine Hat or Calgary or Vancouver, because it is the Trans-Canada Highway," Rudd said, noting transport trucks must take a 200-kilometre detour north instead of using the 30-kilometre stretch that's now closed.

Other portions of the Trans-Canada Highway have been shut on both sides of the Alberta-Saskatchewan border, as well as Highway 41 south to the U.S. Motorists are advised to check road conditions with the Alberta Motor Association before setting out.

With files from The Canadian Press