Much of central and southern Alberta is under a blizzard warning as an Arctic air mass settling over the province brought strong winds and heavy snow.
The Calgary area could see 15 to 30 centimetres of snow on Monday, according to Environment Canada.
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RCMP say 23 vehicles — including four semis — were involved in a multi-vehicle crash north of Calgary. Highway 2 southbound has been closed between Didsbury and Carstairs near the overpass.
Highway 1 has also been closed from Calgary to Brooks, Alta., as Strathmore RCMP deal with another multi-vehicle collision.
RCMP are advising against highway travel until the storm passes. They say emergency crews may not be able to reach all stranded motorists on the highway because of the severe weather.
Blowing snow is reducing visibility on roads in Calgary and on highways outside the city.
Volker Stevin Contracting, which operates snowplows and sanders, said Monday afternoon that it had pulled half of its crews off highways near the Alberta communities of Gleichen, Hussar and Bassano.
“It's a total whiteout out there. They can't see the roads so they become a hazard to the public and a hazard to themselves,” said Volker Stevin's Jack Brown.
"For their safety, we're pulling them out of there."
As of 3 p.m. MT, more than 80 flights in and out of the city have been cancelled at Calgary International Airport, WestJet has eased its restrictions today for people changing flights in and out of Calgary, Edmonton and Grand Prairie, Alta.
Calgary Mayor Naheed Nenshi tweeted Monday that if Calgarians had to be on the roads, they should allow extra time.
"I have to go into work today — darn #yyccc meeting — but if you are able to work from home, please do," he tweeted, referring to a city council meeting.
He later told CBC News that city buses are having some trouble and that C-Trains are full.
The blizzard warning covers all of central and southern Alberta’s major communities, including Red Deer, Brooks, Airdrie, Lethbridge, Medicine Hat and Drumheller.
“The worst conditions are expected near and along a line from Red Deer through Strathmore and south towards Lethbridge, with northerly winds becoming as strong as 50 gusting to 80 km/h and visibilities near zero at times,” Environment Canada said.
Highway 3 at Crowsnest Pass at the B.C.-Alberta boundary was closed as of 9 a.m. MT because of poor driving conditions, officials said.
The community's volunteer fire department said Monday afternoon it was reopened, but officials are still advising against travel.
Many schools in Calgary and around the province have cancelled classes for the day. Calgary's ski hill Canada Olympic Park, which is located in the city limits, is also closed.
The intense winter storm has been moving down from northwestern Alberta since Saturday.
Flurries are expected to continue into Tuesday, according to Environment Canada.
Emergency officials are also looking for a Calgary couple who went camping in Kananaskis, west of Calgary, this weekend. Given the weather conditions, police said they are concerned about their safety.