Another messy winter storm on the way for southern Quebec

Umbrella or shovel? Just about every winter storm this season has been accompanied by a swath of warm air that has changed the snow to rain. In between the changeover, freezing rain and ice pellets have often fallen in significant quantities across the Montreal region.

A Winter Storm Warning is now in effect for metro Montreal and all of southern Quebec for Thursday night into Friday.

I miss the days when a snowstorm was a snowstorm. It seems most of the recent storms that impact Montreal and southern Quebec, are accompanied by myriad of precipitation types. The upcoming winter storm, currently developing over Colorado, will unfortunately be no different. The system is forecast to strengthen as it moves from the Rockies towards the Great Lakes. Numerous computer models have the storm passing very close to Montreal, with just enough warm air moving into our region to change the snow to freezing rain and eventually rain on Friday.

Before then, we are looking at some rare sunshine Wednesday and to start the day on Thursday, before clouds begin to thicken and lower. Temperatures are rather cold Wednesday, with a current reading of -9C (16F) at Trudeau. This morning was the coldest of the winter so far with a low near -13C (9F). We have another cold night on tap tonight, dropping to -10C (14F), before a warm front associated with the aforementioned storm begins to lift north from the Ohio Valley.

A swath of snow will affect eastern Ontario and southern Quebec on Thursday and Friday. Precipitation will likely change to rain across extreme southern portions of both provinces on Friday. North of Montreal, snow will accumulate more than 15cm. (AccuWeather.com)

Precipitation will move into southern Ontario on Thursday, arriving in the Montreal region after the evening commute. As the main area of low pressure moves along or just south of the St. Lawrence Valley, the precipitation will become steadier. South of the low, expect a rain and snow mix, with all precipitation changing over to rain on Friday across the border regions and into New York and New England. Along the track, specifically in the Montreal region, we can expect at least 10cm of snow before mixing with and changing to freezing rain and eventually a cold rain Friday. Unfortunately there may be several hours of freezing rain once again for Montreal.

North of the city, including Ottawa and Quebec City, the precipitation will likely remain as all snow, with over 15cm possible. Weather warnings will be needed for most regions. Details will become more specific as the event draws closer and the track becomes a little more clear. Recent model runs have shown colder air slow to retreat for the St. Lawrence Valley on Friday, further complicating the upcoming forecast.

Temperatures will be at or slightly above freezing on Friday in Montreal. Throughout the storm, expect gusty northeast winds 30 to 50km/h. Some blowing snow is possible, especially over the Laurentians and Quebec City regions.