Flash flooding - power outages sweep Montreal region

One of at least a dozen underpasses that flooded in Montreal after severe thunderstorms on Thursday afternoon. The flooding created traffic gridlock in the central part of the city, with the afternoon commute lasting late into the evening for many. (Photo Courtesy Ragini Patel)

I have been a weather enthusiast since just shortly after I could walk, and days like yesterday still amaze me as to how powerful mother nature can be. It was an extremely active day across eastern Ontario and southern Quebec, with several waves of severe thunderstorms. 

A supercell thunderstorm, one of several observed on Thursday across Quebec and Ontario, advancing on downtown Montreal during the late afternoon hours. (Photo Courtesy George Michel Boutros)

Environment Canada posted rare tornado watches for most of the region, and the storms delivered just after the noon hour, first in the Ottawa Valley, and then unfortunately, during the afternoon commute in Montreal.

Several supercell storms showed rotation, with a confirmed tornado touching down in Barrhaven, southwest of downtown Ottawa. The tornado, yet to be rated, produced significant damage to homes and cars, with at least one injury.

As the storms pressed east, more rotation was observed along the Ottawa River, with a funnel cloud reported in Vaudreuil-Dorion. There was also a confirmed tornado in Mirabel, north of Montreal. This prompted tornado warnings for the entire Island of Montreal. Wind damage was reported across Ile Perrot and the West Island, with several trees and branches down. Wind gusts to 111km/h (68.9 mph) was observed at Trudeau Airport, along with 2cm hail. Dozens of tress were toppled, many on the West Island along the Saint Lawrence River. Power outages mounted, with Hydro-Quebec already having trouble with transmission lines form the north due to forest fires. In all, nearly 500,000 were left without power in the province. This morning that number is down to 216,000 across Qubec, with 86,000 on the Island of Montreal. 

The Barrhaven, Ontario tornado. (Photo via Twitter@TheTaoOvMan)

Flash Flooding

The big problem for most of Montreal turned out to be water not wind. Torrential rain fell with the storms, this time over the central portion of the city. I measured officially 20.4mm in only a few minutes at my home on Ile Perrot, but the storms moved over my location quickly. Such was not the case in Montreal, where 38.2mm fell at the airport, with reports of up to 100mm in several neigbourhoods just to the east of the airport and towards the downtown core. 

At least a dozen underpasses flooded in the usually locations. Oddly enough on just about the 36th anniversary of the Decarie Flood of 1987, the Expressway once again flooded Thursday afternoon. It created traffic gridlock in the central part of the city. Other areas flooded included Cote-des-Neiges, Cote-St-Luc and Lachine, where several cars were inundated up to their roofs.

The severe weather pushed east of the city, with more rotation and funnel clouds observed around Trois-Rivieres.

Friday will be the calm after the storm, with lower humidity and a pleasant high of 26C (79F) under bright sunshine. A rare gem indeed, in what is turning out to be a very odd weather year across our region.

The calm after the storm, as the setting sun reflects off the debris clouds behind the cold front late Thursday on Ile Perrot. (Valley Weather Photo)