Significant freezing rain forecast for Montreal

The combination of freezing rain and strong winds may result in significant power outages across portions of Ontario and Quebec from late Sunday into Monday evening. Up to 15mm of ice accretion is possible in the St. Lawrence Valley. (Hydro-Quebec Photo)

Orange Warning: Freezing Rain. Impact Level: High - Forecast Confidence: High

Strong low pressure will combine with arctic high pressure at the surface to produce and extended period of freezing rain across southwestern Quebec and eastern Ontario from late Sunday into late Monday afternoon. A warm front will be the focus of steady freezing rain along with gusty northeast winds in the St. Lawrence Valley.

Cold arctic high pressure will keep chilly air at the surface here in the St. Lawrence Valley, while a strengthening winter storm moves across the central Great Lakes towards Montreal. A second area of low pressure is forecast to develop south of Montreal on Monday. The combination of both these low pressure areas, will produce up to 15mm of ice accretion across the St. Lawrence Valley. Precipitation may briefly turn to rain across extreme southern areas on Monday, but it will be short in nature as cold air quickly returns.

Travel will be very difficult from late Sunday into the Monday morning commute. Roads and sidewalks will be extremely slippery. The weight of ice on trees and wires may produce significant disruptions to the power grid.

Temperatures will warm very slowly Sunday night, up to 0C (32F) on Monday. As the low moves to our east, a strong cold front will usher in freezing temperatures along with strong northwest winds in excess of 60km/h. Any leftover precipitation will end as snow and blowing snow Monday afternoon. The combination of ice and increasing northwest winds may result in additional power outages.

Plan now for dangerous travel and the risk of extended power outages. Much colder air will follow in the wake of the storm, with lows Monday night in Montreal as cold as -12C (14F). Temperatures will remain very cold into the New Year.