The winter storm warning continues for southern Alberta and police are asking people not to travel unless absolutely necessary.

The storm that pelted the city and surrounding area over the last few days has dumped up to 20 cm of snow in some parts and more is on the way.

City crews have cleared major routes but motorists are struggling to get through on side streets.

The city started applying an anti-icing agent and salt chips on major roads in the early morning hours and will switch to a sand/salt mixture as the temperature drops to provide extra traction.

The city says that drivers should anticipate delays, drive defensively, and slow down.

Highways in southern and central Alberta are also in poor condition.

Heavy winds, blowing snow, icy sections and reduced visibility is making highway travel between Lethbridge and Edmonton treacherous.

The QEII Highway was shut down in both directions north of Calgary for several hours on Saturday but has since reopened.

Environment Canada has issued a Winter Storm Warning and says the snow will taper off through the day on Saturday and temperatures may go as low as -25 with the wind chill.

The system is heading south and an additional 5 to 10 cm of snow is expected for southern regions of the province.

In Lethbridge, wind gusts of up to 60 km per hour caused heavy drifting in several areas, and made it extremely difficult for drivers.

Lethbridge Regional Police are also advising residents to avoid driving if at all possible.

Arrivals and departures at the Calgary International Airport have been disrupted and several flights are cancelled or delayed.

For up to date flight arrivals and departures visit the Calgary Airport Authority Website.