Five to 10 centimetres fell overnight in Calgary on Tuesday, and up to 20 centimetres are expected by the afternoon, warns Environment Canada.

The heavy snowfall warning was issued on Monday for areas in southern Alberta from Didsbury, Alta., south to the border, excluding Banff.

Civic officials say nearly 140 pieces of snow equipment, including snowplows and sanders, are out this morning trying to improve the state of city streets.

“Last night I was up till midnight making sure that our snow removal plan was in place,” Calgary Mayor Naheed Nenshi told the Calgary Eyeopener on Tuesday morning.

High-priority routes are in good condition, but many residential streets have not yet been cleared.

Calgary commuters make their way to work Tuesday morning. Police are warning drivers to be cautious. (Katy Anderson/CBC)

Many Calgary Transit buses are running behind schedule and they have announced some detours.

All buses in the Palliser Regional Schools are not running this morning and there have been some delays and cancellations at the Calgary International Airport.

Road conditions

Between midnight and 8:30 a.m. MT there were 34 collisions, two involving injuries.

The heavy snowfall warning lasted from early Monday afternoon, when a few centimetres fell around the city, and ended on Tuesday around 3:30 p.m. MT.

There were more than 140 accidents in a 24-hour period, according to Calgary police. They are warning drivers to take it slow on the roads today — no matter the type of vehicle you drive, says Duty Insp. Paul Stacey.

"People that have four-wheel drive or all-wheel drive, they can get going better than anyone else, but their stopping ability? No better than anybody."

More officers are not added on snowy days like this; however, more personnel will be transferred to the traffic unit to help respond to collisions, says Stacey.