Alberta's raging flood waters have left a path of destruction throughout much of the southern portion of the province.

Many residents are hoping the weather will subside so the cleanup can begin, but showers and thunderstorms are tracking down from the north towards some of the hard-hit areas.

"In Calgary tonight, showers and thunderstorms are possible, and they could even bubble up again Saturday afternoon," said CBC meteorologist Danielle Savoni.

She said there is the possibility of more precipitation late Sunday as well.

"It's hard to tell with these types of storms where exactly they will pop up, but some localized areas in the south end of the province could see another five to 10 millimetres through the weekend."

Alberta's deep south could also see more rain.

The forecast in Lethbridge tonight is mainly cloudy with 60 per cent chance of showers, and a risk of a thunderstorm early this evening. Saturday calls for a mix of sun and cloud and a high of 18 C.

Southeast corner of Alberta braces for floods

But Lethbridge, as well as Medicine Hat, haven't seen local rivers peak yet. The municipalities declared a state of emergency Friday afternoon.

In Medicine Hat, residents in low-lying areas were told to leave their homes along the river. The mandatory evacuation is expected to include about 3,800 homes and 10,000 residents.

Flood destruction has been seen in many areas in the foothills west of Calgary, which saw roughly 200 millimetres of rainfall since Wednesday night.

Rain in Banff is expected to end early this evening, and then be partly cloudy with 30 per cent chance of showers. There is a 60 per cent chance of showers in the late afternoon on Saturday in the mountain town and a risk of thunderstorms.

Banff issued evacuation orders for some areas on Friday, and officials say people should avoid areas around the Bow River and areas south of the Banff Avenue bridge. 

In High River, where floodwaters caused major damage, rain is forecasted to end this evening then be cloudy with 60 per cent chance of showers. The area, which is still under a mandatory evacuation, could see another 10 millimetres of rain.

Saturday will see a 40 per cent chance of showers in the town located roughly 60 kilometres south of Calgary, with a risk of a thunderstorm late in the afternoon.

Red Deer has a 30 per cent chance of showers this evening with a risk of thunderstorms. There is a 30 per cent chance the city north of Calgary will see showers in the morning.

Calgary Mayor Naheed Nenshi said the water levels have reached a peak, but have not declined.

"We've sat at the same level for many, many hours now," Nenshi said earlier Friday. "There is one scenario that would it go even higher than this, so you'll either see the Bow River continue at this level for many hours or you will see it grow even higher and we're prepared for that eventuality."

Television images showed trees and debris being swept down the swollen Bow River, which flows through central Calgary and crested at around 1,500 cubic metres per second overnight, more than five times the normal flow rate for this time of year.

Flows on the Bow, and Elbow River which flows into it, were around three times as high as during the last serious Calgary floods in 2005, which caused an estimated $400 million worth of damage.

No figures are available for damage from the latest floods.

Alberta lies to the east of the Rockies, and many parts of the province are normally very dry.

But a stubborn area of high pressure in Alaska and northern Alberta has pulled a stream of moisture up into southern Alberta from the United States, causing the heavy downpours.

With files from The Canadian Press