Pattern change will result in snow & cold for Montreal

The first major snowfall of the season is forecast for many locations across southern Quebec on Friday. Montreal will have a mix of snow and rain with this system. A more significant storm is expected to develop by next Tuesday, with perhaps the first snowstorm of the season for Montreal.

A sharp pattern change is expected this weekend, with cold air pouring into southern Quebec and Ontario behind the next storm. Two areas of low pressure will affect the region Friday and Saturday, with a rain/snow mix forecast in Montreal. Thursday will be the last mild day for the foreseeable future, with a mix of cloud and sun, and a high of 7C (45F).

On Friday, clouds will thicken as low pressure approaches the region form the Great Lakes. A second low is forecast to move through New England, with a decent fetch of moisture pushing north over southern Quebec. Rain will develop late in the day, mixing with snow Friday night. Most of the St. Lawrence Valley can expect a cold rain from this system, but the upper elevations of the Laurentians and Townships may be looking at accumulating snow by Saturday morning. North of Montreal, the cold air will arrive sooner, with 15 to 20cm of snow possible. Gusty winds are also expected with this storm, 50-70km/h. Behind the low pressure, cold air will pour across the Great Lakes, with the first lake effect snowstorm forecast in Ontario and portions of western New York.

Prepare for winter driving if you have travel plans north or west of Montreal this weekend. Also now is the time to install those winter tires.

High pressure will then nudge into our region on Sunday, with the coldest airmass of the season expected so far. The high on Sunday will be at the freezing point, with overnight lows dropping to -6C (21F). The cold weather is expected to persist next week, with mid-December temperatures forecast.

First snowstorm for Montreal?
Another major storm is expected to develop along the US east coast by late Monday, possibly impacting Quebec with another snowstorm next week. This system may bring Montreal our first significant snowfall of the season. Some models are hinting at more than 15cm of snow in the city. There are still many forecast details to work out, as is common with Nor'Easters.