Strengthening low pressure will move along the St. Lawrence Valley late Sunday and Monday bringing Montreal the first widespread snowfall of the season. Up to 10cm may fall in Montreal, with more than 15cm north and east of the city. The snow will change to rain from Montreal south on Monday.
Special Weather Statement for Montreal for 5-10cm of snow Sunday evening.
We are in the process of cooling down early Saturday morning after another very warm high of 15C (59F) in Montreal on Friday. Our unusual November trudges along, a month that has featured an all time record high of 22.4C (73F), as well as snowfall and temperatures as cold as -7C (19F).
On Saturday, we can expect a rather cloudy day, with slowly falling temperatures towards the freezing point by late this afternoon. Overnight lows in Montreal tonight will be cold, down to -6C in the city. On Sunday, our attention will shift to developing low pressure over the Ohio Valley. This storm is forecast to strengthen as it moves along or just south of the St. Lawrence Valley on Monday. My current thinking is snow will develop over southwestern Quebec after 4pm on Sunday afternoon. The snow will likely persist into the overnight hours before mixing with rain early Monday morning. Before the mixing, we could be looking at 5 to10cm of snowfall for Montreal, less across the South Shore and perhaps as much as 15 cm over Laval and the North Shore. There is also a chance of some freezing rain during the transition. If that occurs, it would be in the pre-dawn hours Monday morning. Expect snow covered and slippery roads for the Monday morning commute.
Gusty winds of up to 60km/h will accompany the precipitation, especially in the St. Lawrence Valley. The winds will be out of the northeast to begin with, which will help keep temperatures below freezing in Montreal. The high on Sunday will reach 0C (32F) late in the day, before rising overnight into Monday, well above freezing. Just how warm we reach on Monday, will be determined by the exact track of the storm. The current forecast high is 8C (47F), but I really believe that is optimistic.
Mainly snow is forecast in the Laurentians and Quebec City. Weather warnings may be required for those regions. Similar snowy conditions are forecast for Ottawa and the 401 corridor towards Kingston. Snowfall totals will be 10-15cm along the Ottawa Valley, dropping to less than 5cm as you approach Lake Ontario.
Conditions will improve Monday evening, but it will turn quite cold behind the system, with lows dropping to -4C (25F). Another system will arrive late Wednesday, with perhaps more snow and rain.
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