Polar vortex will bring up to 20 centimetres of snow to Calgary, keep highs below freezing

A dominant ridge of high pressure brought unusually warm weather to southern Alberta over the weekend, setting temperature records in several communities.

According to Environment and Climate Change Canada, 25 communities set new record highs including areas like Waterton (17.9 C), Pincher Creek (20.1 C), Claresholm (21.5 C), Banff (16.0 C), Bow Valley (Provincial Park) (18.1 C), Sundre (18.6 C), Jasper (20.2 C), Grande Prairie (21.3 C) and Fort McMurray (14.7 C).

Calgary did not make history Sunday, despite recording a maximum temperature near 16 C.

Monday will be another day with highs in the mid-to-high teens for much of southern Alberta, including Calgary, but that heat is not going to last.

A shift in weather patterns will see the polar vortex start to wander south, funnelling Arctic air into the western prairies late Monday.

That frontal system is expected to produce blustery conditions along the leading edge as it tracks south. Depending on the atmospheric profile, some communities in northern Alberta will experience rain before it transitions to snow as the temperature plummets.

By the time this system hits southern Alberta, that precipitation is expected to show up as snow.

Some well-positioned highs and lows will anchor this system and cause it to essentially stall out along the foothills with intensifying and persistent snowfall for at least a couple of days.

Calgary is likely to first notice the winds shifting to come out of the north on Monday, making it feel slightly colder than the ambient temperature.

Tuesday’s daytime high of 4 C will come early in the day and most of the incoming precipitation will fall as snow.

Calgary's seven-day temperature trend for March 18-24, 2024. (CTV News)

The snowiest day of this event in Calgary is expected to be on Wednesday with between 10 to 15 centimetres possible by the end of the day.

March is typically the snowiest month in Calgary with an average monthly snowfall of 22.7 centimetres. However, a snowy start to March 2024 had Calgary sitting above that monthly snowfall average after 25.3 centimetres of snow was recorded from March 1 to 6, 2024.

Alberta and B.C. snowfall forecast for Wednesday, March 20, 2024. (CTV News)

Whatever snow does fall this week is unlikely to melt immediately. The forecast from Wednesday until Sunday includes overcast skies with daytime highs between -4 C and -9 C, and overnight lows between -10 C and -16 C.

Calgary five-day forecast for March 18-22, 2024. (CTV News)

The average range in Calgary this time of year is 4 C and -8 C.