Messy weekend storm to impact Montreal

As we witnessed Wednesday morning, it does not take a huge amount of snow to create dangerous driving conditions. A burst of snow during the morning commute lead to dozens of accidents in Montreal. (ValleyWeather Photo)

Winter is desperately trying to establish a foothold in southern Quebec. But with no real cold air in place, it has been difficult at best. The little snow that has fallen to date, including the 4 to 5cm of snow that fell on Wednesday in Montreal, melts away very quickly. Even milder air is expected on Friday, as high temperatures in southern Quebec climb to 5C (41F). Skies will tend mostly cloudy, with just  few sprinkles or flurries possible.

Marginally colder air is expected in the St. Lawrence Valley Friday night and early Saturday, with lows down to -1C (30F). On Saturday, strengthening low pressure will move towards southern Ontario and eventually down the St. Lawrence Valley. As with every storm this fall, warm air will arrive with the storm. Precipitation is expected to overspread eastern Ontario in the morning hours, spreading into southern Quebec and metro Montreal during the afternoon. At this time, it appears enough cold air will remain at the surface in to allow for a messy mix of snow, freezing rain and eventually rain from Montreal south. 

A good 10 to 20mm of precipitation if expected with this system, mostly falling as rain in Montreal, but there may be a few hours of freezing rain at the onset, especially between Montreal and Ottawa. Further north, mainly snow will fall, with 10 to 20cm possible. The amount and type of precipitation will need to be fine tuned as the event draws closer, and the path of the low becomes a little more precise. For now, plan on slick travel Saturday into the overnight hours across the entire region. By Sunday, enough warm air should change most of the precipitation to rain in Montreal and points south.

I am also watching the potential for a much larger winter storm for the middle portion of next week. There remain many details to iron out at this time.