Pattern flip this week to bring Canada colder air, major snow to some

A big Alaskan ridge will help funnel cooler air into the eastern half of Canada this week

Many Canadians have enjoyed a taste of warmth in recent days, but winter isn’t done with us just yet.

A change will sweep across much of the country this week, forcing a surge of cooler air to displace the unseasonable warmth of late.

This cooler pattern could even arrive with a threat for heavy snow in some spots.

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Pattern change arrives for Valentine’s Day

It’s been pretty warm of late. Above-freezing temperatures allowed liquid rain to fall all the way into far northern Ontario toward James Bay to end the week.

Toronto, Ottawa, Hamilton, and London all saw top-ten warmest February days on record Friday, with daytime highs in the mid-teens in the south and just shy of 10 degrees in the nation's capital.

Ontario top-ten warmest Feb days

A large upper-level ridge building up the West Coast into Alaska will be the major player in our pattern flip.

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A good rule of thumb is that Eastern Canada gets the cold air Alaska doesn’t want. As a result of that western ridge, a big trough will develop over Eastern Canada and drag some of that Arctic air southward. This won’t be the strongest pulse of the polar vortex, but it’ll bring a noticeable chill.

National Atmospheric Heights Tue Feb 13 2024

If you’re in Alberta, don’t worry—you’re not the target of this push of cold air this time around. The general breakdown will see warmer air pushed into Labrador on the eastern side of the trough, while Arctic air gets pulled into the Great Lakes on the western end of the trough.

Closely watching an East Coast nor'easter

A powerful nor’easter gathering steam south of the border will threaten much of Atlantic Canada with significant snowfall totals and gusty winds, just in time for Valentine's Day

Atlantic snow outlook

MUST SEE: PHOTOS: Record-setting snowstorm drops 100+ cm of snow on Nova Scotia

Some uncertainty remains in the ultimate track of the storm, which would affect precisely where the heaviest snow would fall. Folks around Halifax, Sydney, and St. John's should be on alert for impactful snowfall from this system.

Prepare to adjust travel plans through the middle of the week. Take advantage of Monday’s calm weather to make any last-minute preparations you may need before the storm arrives.

WATCH: High-impact nor'easter on the way for Atlantic Canada