First snowflakes of the season on the horizon for Montreal

Snow has already fallen this week in spots across the Eastern Townships into the White mountains of New Hampshire and parts of Vermont. More snow is expected through Monday, with locations like Jay Peak, Vermont picking up as much as 20cm. Snow may also fall in the valley locations by Sunday night, including Montreal. (NHDOT Photo)

Measurable snow is possible by late Sunday into Monday morning for parts of southern Quebec.

First of all, if you do not have your snow tires on yet, now is the time to seriously consider doing so. Our weather will turn unseasonably cold over the next week, while a series of clipper systems moves southeast across Ontario and into New England. This will produce enough cold air for some snow to fall. While this will not be a big storm, the first snow of the season in any form usually sparks panic on the roads. Be ready!

Alberta Clippers are weaker areas of low pressure that develop in the southern Prairies and move rather quickly east across Ontario and Quebec. They often gain a little strength when the waters of the Great Lakes have yet to freeze. Clippers usually have limited moisture, so they are not our big storms, but they do produce squally weather, strong winds and a sharp drop in the temperatures on the back side of the systems.

November has already produced more seasonable weather in Montreal, after a warm September and October. Snow may fall next week across parts of southern Quebec. (Valley Weather Photo)

We have three such systems forecast to move across our region through Monday. The first on Wednesday, will produce showers and gusty west winds. Wind speeds may top 60km/h in the St. Lawrence Valley. Temperatures will only reach 6C (43F) for a high, followed by morning lows close to the freezing point. On Thursday, behind the first clipper, temperatures will hold steady at 2C (36F), along with blustery conditions and perhaps a snowflake or two. The chilly air will persist into Friday.

Another clipper late Friday, will pass north of Montreal, allowing some warm air to briefly enter the forecast. After a cold morning, highs will reach 8C (47F) on Saturday. On Sunday, the strongest of the three clippers will move south of Montreal, dragging a potent cold front behind it. Temperature will fall to below freezing Sunday night as the coldest air of the season to date arrives across Ontario and Quebec.

Any rain Sunday will change to wet snow overnight into Monday morning across the Ottawa Valley and into Montreal, with a slushy centimetre or two possible for many locations. Temperatures will drop below freezing Sunday night and likely remain near 0C (32F) for highs on Monday. Tuesday will remain breezy and cold, with flurries and a high near 2C (36F).

By the way, how cold is the air over Northern Canada? On Wednesday morning as I write this post, Eureka, Nunavut is -37.6C.