Severe flooding has hit parts of western Canada this week after torrential rains pushed rivers well beyond normal capacity.

Raging floodwaters in southern Alberta have washed out roads and bridges and have forced nearly 100,000 people in the city of Calgary to evacuate their homes.

In Calgary, the mayor ordered some 7 percent of the city’s 1.1 million residents to leave their homes overnight, Reuters reports. As of Friday, over two dozen low-lying neighborhoods are under a mandatory evacuation warning. Elsewhere in the province, flooding closed portions of the Trans-Canadian highway and cut off the resort town of Banff in the Canadian Rockies, writes the Associated Press.

High River, a town in southwestern Alberta, found itself engulfed in raging floodwaters, and more than half the town’s residents had to be rescued from their rooftops.

Rainfall warnings

Environment Canada – the Canadian weather service – says some areas have received over 100 mm (3.9″) of rain since Wednesday night due to a stubborn low pressure system. The agency has issued rainfall warnings for three regions in southwestern Alberta, including Banff National Park, and up to another 40 mm (1.5″) is forecast through tomorrow.

In a tweet, Rob Davis – a meteorologist with The Weather Network – wrote that the Bow River was flowing through Calgary at an all-time record of 1300 cubic meters per second.

Calgary has received 120.6 mm (4.7″) of rain this month, which is about 51 percent above its June average. Higher elevation areas were in the bulls-eye for rain yesterday, with some places southeast of Calgary recording over 130 mm (5.1″) in 24 hours (see map).

A remote controlled tricopter captures dramatic flood in Okotoks, Alberta via YouTube

The trough bringing cool, unsettled weather to western Canada comes at the same time an expansive ridge of high pressure has brought record heat to Alaska and the Canadian Arctic.

Fortunately, the sudden deluge will begin to subside over the weekend, giving flood-stricken areas a chance to clean up from the damage.