New Year's Eve snow expected in Montreal and Ottawa

A private contractor puts down a layer of salt in Vaudreuil on Friday evening. A messy mix of 5cm of snow and 12mm of freezing rain, combined with dropping temperatures, have left ice everywhere in metro Montreal. (ValleyWeather Photo)

The weather roller coaster typical of most El Nino winters is well underway in southern Quebec. After a messy mix of rain and freezing rain on Friday in Montreal, the mercury soared up to 6C (43F) during the overnight hours into Saturday. However early Saturday, a potent cold front dropped the temperature down into the minus teens just a quickly. In Montreal, the temperature fell 11 degrees in just a few hours, with the morning low Sunday at -15C (5F). The result is plenty of ice around, especially on secondary roads and parking lots.

High pressure will crest over Ontario and Quebec on Sunday, with just some high cloudiness expected. On Monday, a potent low pressure area and frontal system developing in the US Midwest will approach Montreal, accompanied by a wide swath of precipitation. As with the other storms this month, mild air will return as well. This is a pattern that was established early in December, and shows no real sign of changing soon.

Snow and Freezing Rain
The difference this time is the storm track may be a little to the south of Montreal, allowing for marginally cold air to remain here in the St. Lawrence Valley. We may have enough cold air remaining to keep the precipitation frozen. At this time, expect snow to develop after 8pm Monday night and persist into the New Year, mixing with freezing rain from Montreal south. Eventually all precipitation should change to rain south of Montreal, but remain as snow north and east of the city. Accumulations will range from at least 5cm in Montreal and Ottawa to as much as 15cm in Quebec city and the Laurentians. Regardless of what falls with this system, travel will be impacted across the entire area including southern Quebec, eastern Ontario and northern New England. If you have plans for New Year's Eve, expect snow covered roads and reduced visibility.

The system will move into northern Maine on New Year's Day, with gusty winds, dropping temperatures and flurries forecast for Montreal to start 2019. I will post further updates on the storm as the track becomes clearer later today.