Extreme cold warnings expanded across country; snowfall warnings remain for southern Alberta

A persistent weather pattern is funnelling arctic air across the Prairies, which forced Environment and Climate Change Canada (ECCC) to issue extreme cold warnings late Thursday.

The national weather agency expanded those warnings Friday night, and as of 7:30 p.m., including the Yukon, Northwest Territories, Alberta, Saskatchewan, Manitoba and Ontario.

Wind chill values under the warned areas are likely to drop to at least -40 at times, especially early in the morning Saturday.

At the same time that colder air is meandering south, a slow-moving, moisture-laden system is edging north into southern British Columbia.

That Pacific air mass is going to track east toward the southern Rockies, where it will meet up with the western edge of the polar air mass and deliver up to 15 centimetres of snow for the southwest corridor of Alberta.

Snowfall warnings issued from ECCC note visibility is likely to be compromised in this area and road conditions will deteriorate when the two systems collide.

An incoming ridge of high pressure heading up the U.S. west coast will finally dislodge this stagnant pattern early next week, and daytime highs in southern Alberta will rise quickly.

By Wednesday, it could be as warm as 5 C in Calgary, or eight degrees warmer than the average high of -3 C, a sharp change from Friday’s high of -15 C, which equals the average overnight low value this time of year.