Flash flooding in northwest as Calgary gets walloped by weather again

A severe thunderstorm that rolled through Calgary on Thursday evening continued to cause issues on the roads well into the night.

Police were warning drivers to use caution and find other routes in areas that were hit hardest.

Thunder, lightning, heavy rain and hail came down around the supper hour.

Traffic was at a standstill along the Trans-Canada Highway heading into Calgary due to flooding.

One car could be seen partially submerged near Stoney Trail.

Drivers were being directed away from the area, causing delays.

Environment and Climate Change Canada says the thunderstorm was slow-moving, producing a lot of rain and dime-sized hail in some areas.

"Because it wasn't moving very fast, that all fell over a very small area, relatively speaking," said Justin Patten, a meteorologist with Environment and Climate Change Canada.

"What (the hail) does is it can plug up storm drains and really make the flooding situation worse.

"The rain that falls on roadways and infrastructure has nowhere to go but to the storm drains, so it can be easily overrun in situations like this, where we have really slow-moving thunderstorms."

A severe thunderstorm that rolled through Calgary on Thursday evening continued to cause issues on the roads well into the night.

Patten says there were reports of 35 to 85 millimetres of rain in northwest Calgary alone.

"That's quite a lot of rain to fall over a short period of time," he said.

The weather agency also urges people to use caution during such events.

"Motorists in particular are of concern," Patten said.

Water was flowing fast on many roads, especially in the northwest.

A severe thunderstorm warning went into effect earlier Thursday evening but was later lifted.

Rain was expected to linger throughout the evening, with another five to 10 millimetres expected.