Environment Canada has issued a heavy snowfall warning for Calgary and for the bulk of southern Alberta — from Airdrie south to the American border.

The warning moves into a winter storm alert as it moves south.

Police say the falling snow and dip in temperature is creating some problems for drivers Thursday morning.

Duty Insp. Darren Leggatt says it's time Calgarians get into a winter driving mindset again.

“With the freshly fallen snow, and the fact the road conditions are likely to deteriorate and slow things down on the roads anyway, I think starting the mindset from the perspective of patience and understanding one is going to have to take their time today," Leggatt said.

Accidents building up

Police say 194 collisions were reported from midnight to 4 p.m. MT Thursday — 12 of those involved injuries.

The City of Calgary says crews began preparing for the snowfall last night.

"We're putting material down, some anti-icing material in anticipation of the snow," said Jennifer Thompson-Goldberg.

Wet roads and falling snow made for a slow commute Thursday morning. (Kyle Bakx/CBC)

"And then again with the warm surface temperatures, and the previous salting and material we put down, the snow has just melted when it has hit especially those main commuter routes.

"Once it really starts to snow and we are into the season and we are expecting those heavier snowfalls, we are working seven days a week, 24 hours a day.”

Meanwhile, Brooks RCMP say icy road conditions were the likely cause of a rollover south of Calgary Thursday morning that killed two people.

Police say an Econoline passenger van lost control on a bridge on Highway 36 and rolled several times as it crashed down a steep embankment at about 9:30 a.m. MT.

No names have been released.

Albertans living in the areas highlighted in red are being warned to brace themselves for a blast of winter weather. (weatheroffice.gc.ca)

Airport delays, but no parking ban

Several flights leaving Calgary have been delayed, and some have been cancelled because of the weather. Check the Calgary International Airport's website for a detailed list of flight schedules.

The City of Calgary says despite the potential for significant snow, a parking ban will not be called prior to Sunday.

Environment Canada says Calgary could get up to 15 centimetres of snow by tonight.