Snow in the Prairies and record-breaking temperatures in the East cap a week of weather extremes

The past week has been one of weather extremes.

In the Prairies: Between 15 and 30 cm of snow in Calgary and Edmonton last Wednesday and Thursday. The same or more for Regina and Saskatoon from Friday and Saturday. Winnipeg under nearly 30 cm of snow while the small west-central Manitoba town of Mafeking is buried under 65 cm! Strong winds and frigid temperatures followed, just to add insult to injury (so to speak).

In the Great Lakes area and along the St. Lawrence: Mild temperatures last week. A bit of rain on Saturday and some freezing rain for eastern Ontario and southwestern Quebec on Sunday morning. On Sunday afternoon, a record high temperature in Toronto of 18.4 degrees C, beating a 74-year old record of 17.2 degrees C from November 11th, 1938, and record breaking high temperatures are expected in the Montreal area today!

Prairie snowstormPeople in parts of Saskatchewan, Manitoba and northern Ontario are coping with a major snowstorm, with severe weather warnings still in effect in Manitoba

[ Related: Future temperature rises underestimated by current climate projections ]

What's causing this extreme contrast between these two regions of the country? I guess we can blame the United States for this one...

Last Wednesday, a scenario we've already seen a few times since last month played out again, as a weather system moved up from Idaho and Montana, and buried southern Alberta, Saskatchewan, Manitoba and northwestern Ontario in snow, leaving behind strong winds and frigid temperatures in its wake.

Even as that system fizzled out, a much larger weather system was brewing over Colorado. This new system quickly headed northeast towards Lake Superior, dumping more snow onto the prairies and pushing a blob of very warm air ahead of it to the east, which drove the mercury up in southern Ontario on Sunday and will do the same for eastern Ontario and Quebec today.

Lined up north-to-south along the cold front associated with this Colorado Low is a line of storms, which is now passing through the U.S. Midwest. With the Low centered over northern Ontario now, and expected to move off to the northeast, that line of storms is likely to sweep over the entire eastern half of Ontario, through Quebec, and the Atlantic Provinces over the next couple of days.

[ Related: Blame Canada for ancient and massive 1,300-year 'Big Freeze' ]

The temperatures behind this cold front drop significantly, so residents of Ontario and Quebec better get out and enjoy the warm weather, as today's double-digit temperatures will drop into the single-digits for the rest of the week.

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