Messy mix of precipitation expected for Montreal

Allow yourself extra time for the Wednesday morning commute across southern Québec. A messy mix of precipitation is forecast, starting this evening and tapering off late Wednesday. Between 5-10cm of snow, along with freezing rain and eventually rain is expected across the entire region.

Winter Weather Advisories are in effect for northern New York, New England and Eastern Ontario. They may be extended into southern Quebec later today.

Tuesday morning was one of the coldest so far this season, with low temperatures across the southwestern Quebec generally between -5C and -10C (14F-23F). The coldest reading I could find was across the Laurentians where several locations were in the middle minus teens.

Today will be sunny and cold, with increasing northeast winds and a high temperature near the freezing point in Montreal. Low pressure will move from the central plains into the Great Lakes on Wednesday, passing well north and west of the Montreal region. A warm front advancing into Ontario and Quebec this afternoon and tonight, will set the stage for several hours of mixed precipitation.

Clouds will thicken today, followed by snow spreading across the Ottawa Valley and into southwestern Quebec late this afternoon and this evening, persisting well into the overnight period. As warmer air erodes the cold air at the surface, the snow will change to rain, with the risk of freezing rain during the transition. Before the changeover, a good 5cm of snow is possible in Montreal, with 5 to 10cm expected north of Montreal and in the Ottawa region, as well as the eastern Townships. Some higher elevations across the Townships and Vermont may see up to 15cm. Locations that see freezing rain, such as Cornwall and Massena, may se as much as 10mm of ice accretion.

As the warmer air moves into the entire region Wednesday, temperatures will rise above freezing to around 3C (38F) in Montreal, with all precipitation changing over the light rain or drizzle.

If you have travel plans on Wednesday, expect highly variable conditions, with mixed precipitation and the likelihood of snow covered and icy roads in many locations.

On Thursday, a cold front will bring in an arctic airmass that will persist Friday and into the weekend, with temperatures falling through the day, along with gusty northwest winds. A few flurries are possible as well. Temperatures will be the coldest of the season so far by Friday, dropping from 5C (41F) Thursday, down to -8C (18F) by Friday morning and remaining fairly steady during the day. The low Saturday morning will be a chilly -12C (10F).