Strong October thunderstorms produce flooding in Montreal

Strong thunderstorms produced widespread flash flooding during the evening commute in Montreal. (ValleyWeather Photo)

Frost Advisory in effect for southern Quebec.

A slow moving warm front became the focus for strong thunderstorms on Tuesday across southern Quebec and especially here in the Montreal region. Torrential rain fell on the city between 2 and 6pm producing widespread flash flooding across several regions of the city. Wicked lightning and thunder accompanied the storms, more common for Montreal in July than October.

A record breaking 48.4mm of rain fell at Trudeau Airport on Tuesday, surpassing the previous daily high of 34.3mm set in 1945. The rain overwhelmed sewers flooding basements and closing several roads including Highway 20 at Boulevard Angrignon. The flooding and heavy rain made for a long evening commute for many. The storms were part of the same weather system that produced record high temperatures across southern Ontario. Over a dozen record highs were observed on Tuesday, including 31.8C (89F) in Toronto, surpassing the previous record of 29.5C (85F) set in 2002. It was also the warmest high ever recorded in that city in October. While southern Ontario was basking in summer warmth, flurries and temperatures near 0C (32C) were occurring across northwestern portions of the province.

Montreal remained in the cool, moist air to the north of the front for most of the day, finally warming to 17C (63F) by the early evening.

The new section of Highway 20 near Boulevard Angrignon, was turned into a lake during the severe thunderstorms Tuesday afternoon. Transport Quebec was forced to close the road in both directions , snarling traffic for hours. (CTV)

First frost
Behind this weather system, much colder air will pour into southern Quebec, with a good chance for the first frost of the season early Wednesday morning. Frost advisories are in effect for the entire region, including metro Montreal, with overnight lows forecast between 0C and 2C (32 to 36F) in the city and as cold as -3C (27F) north of Montreal. Frost is also expected in eastern Ontario away from the St. Lawrence River.