Significant freezing rain event for Montreal on Wednesday

This event looks quite similar to the April 2023 storm that knocked power out to 1 million Hydro-Quebec customers for up to 5 days. Between 30-40mm of freezing rain fell during that storm. (Valley Weather)

STORM UPDATE...

Freezing Rain Warning for the Montreal region for 20-30mm of frozen precipitation.

Freezing rain is forecast to start overnight and change to rain late Wednesday. There is still a chance the system could pass just to our west, allowing slightly warmer air to arrive, resulting in more liquid than frozen precipitation for Montréal.

An Orange Level weather warning has been issued by Environment Canada for a large portion of southwestern and western Quebec including the metro Montreal region. This is the first orange warning for Montreal since the new colour code system was introduced in late November.

For Montreal, the forecast and impact levels are high, but there is still some questions that remain regarding surface temperatures. Strengthening low pressure will develop over the midwest United States on Tuesday, moving towards the Great Lakes and St. Lawrence Valley. At the same time a backdoor cold front will slip south of the Montreal region late today, allowing colder air from the north to filter into the region. Winds will shift from the south to northeast, and gust to 40km/h.

Precipitation from the storm system will begin to override the cold air at the surface later tonight, with showers eventually changing to steady freezing rain after midnight. After a daytime high close to 10C (50F) on Tuesday, Montreal will drop to 0C (32F) by midnight. Winds will shift form the south to northeast, gusting up to 40km/h at times. Temperatures will remain near the freezing point on Wednesday.

Freezing rain will persist into Wednesday across the greater Montreal region and especially the Ottawa Valley. Temperatures may rise above freezing from Montreal south allowing the freezing rain to changeover to plain rain Wednesday afternoon. The rain may be heavy at times. A total of 25-50mm of moisture is available with this system.

The temperature profile will be very close to the freezing point, with a range of precipitation types possible across the metro region. Another factor will be the warm temperatures that have preceded the storm. This may allow road surfaces to remain just wet, while ice builds up on elevated surfaces such as bridges, trees and power lines, as it did in April 2023.

The setup looks very similar to that of the April 2023 Ice Storm, that cut power to over 1 million Quebec homes and businesses, some for up to 5 days. The storm also did tremendous damage to trees and cars.

Expect power outages and travel delays on Wednesday.

Precipitation will taper off to flurries on Thursday, as temperatures drop significantly behind the storm.