The forecast for regions across Canada that will see a white Christmas becomes slightly clearer with each passing day. Our snow scale runs from a zero to 100 per cent chance, and out of 23 Canadian locations, 18 of them are of high chance or guaranteed.
The high confidence for the majority of the selected locations is due to the dynamic atmospheric pattern that will reliably supply Arctic air throughout this week leading up to Christmas.
Like blowing a substantial lead in a hockey game, the coast of B.C. will see its newfound snowpack dissolve by Christmas Eve as temperatures soar, compliments of the Pacific jet stream returning. The snowpack across higher terrain and through the Interior is decidedly safe.
The Prairies are seeing the highest odds in the country for a white Christmas. The milder Pacific air for the upcoming weekend hits the dense wall of Arctic air, and temperatures will warm, but not enough to melt the snow before Christmas Day.
Ontario and Quebec:
Ottawa recently had one of its deepest snowfalls on record in December last week, so we're comfortable enough to lock in a white Christmas for the city.
Much of southern Ontario is uncomfortably green leading up to Christmas, but a system will most likely put down a carpet of white on the days leading up to the 25th. Warm air will wrap into the system and bring periods of rainfall for some. However, temperatures plummet behind the low and wrap-around snowfall and snow squalls will dominate the weather story leading up to Christmas.
Quebec just finished a marathon snowfall event, so the snowpack is there. This powerful, late-week low will attempt to chip away at the snowpack, but cold air rushing behind is highly likely to save the chances of a white Christmas for Montreal.
Significant variability exists across the region and recent snowfall events have been highly elevation-dependent. Nova Scotia will largely miss out on a white Christmas this year, but head inland across New Brunswick, and it quickly becomes a different story.
For St. John's and the Avalon, it'll be a tough ask to hang onto the swipes of snowfall this week as the long-range hints at warming air surging up the Atlantic before the 25th of December -- all associated with a developing storm. Areas inland and farther west stand to have higher odds of holding onto a dwindling snowpack.