Saturday, November 19, 2016

Calm before the storm for southwestern Quebec

Blizzard conditions pounded sections of Minnesota and northwest Ontario on Friday. Numerous accidents were reported along with several fatalities from the first storm of the season. The snow arrives in Montreal by Monday. (KARE 11 Photo via Twitter)
Dense fog has developed once again this morning in Montreal. The fog is expected to dissipate by mid-morning allowing sunshine to warm temperatures to 13C (55F). The record high for November 19 is 16.7C set in 1953. We have an outside shot at this, if the wind can shift out of the northeast. On Friday, a northeast breeze resulted in a high of 9C (48F) in Montreal. At the same time, over a dozen locations in Ontario reported record highs, including Windsor at 21.6C (71F), eclipsing the record of 18.9C set in 1971.

We now shift our attention to the first winter storm of the season. Low pressure over northwest Ontario this morning is forecast to move eastward into western Quebec by Sunday. A strong cold front will sweep across the St. Lawrence Valley overnight with rain developing. Temperatures fall rapidly behind the front, with rain changing to snow in Ontario during Sunday and towards Montreal by Sunday night. A special weather statement is currently in effect for southern Quebec as well as eastern Ontario. South of the border, winter storm warnings are in effect for the St. Lawrence Valley of New York, as well as the Adirondacks and Green Mountains.

So what does all this mean? Basically we are looking at a 24 to 36 hour snowfall from late Sunday into Monday night for the entire region. Amounts will be based on elevation and how rapidly any location changes form rain to snow. At this time, the heaviest amounts are expected across the mountains of southern Quebec and New England. However, western regions of our forecast district, including Cornwall and the Seaway Valley, may see 10 to 15cm of snow by late Monday. I think Montreal will settle into the 5 to 10cm range. Temperatures will turn much colder, and strong northwest winds are forecast, a far cry from what we have been experiencing so far this fall.

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