Severe thunderstorm in Montreal - July 19th, 2013

A video compilation showing severe thunderstorms advancing onto the island of Montreal from the NW during the mid-afternoon hours. Thunderstorms were developing within the warm sector of the associated low with the aid of a pre-frontal trough to the NW. Brief powerful thunderstorms also formed early in the morning, around 6:40-7:10 a.m. EDT, producing some particularly loud thunder. Squall line thunderstorms began influencing many areas of S. Quebec by 3:25 p.m. EDT, the first of which was in the form of a bow. This trough coincided with an extremely unstable environment (SBCAPE on the order of 3000-35000 J/kg), owing to dewpoints in the low 20s C (maximum hourly dewpoint of 24.3 C) and strong low-level lapse rates (weak mid-level lapse rates). In addition, progressively larger unidirectional shearing fields/hodographs assisted with storm enhanced coverage and organization, consistent with the gradual influence of the jet stream. This environment was conducive for thunderstorms to produce frequent/intense lightning, strong downbursts of wind, and torrential rainfall. Nearly an inch of rainfall (some localities reporting even more rainfall) fell in less than an hour. Thunderstorms could be seen NW of the Montreal area just around 3:00 p.m.

Multiple tornado warnings were issued by Environment Canada for areas near Drummondville, Chateauguay, Granby though tornado touchdowns have yet to be confirmed. Tornado watches had also been in place for the city of Ottawa. Strong winds were particularly an issue, causing localized damage (mostly to trees) while cutting electricity to approximately, at one point, 550,000 customers across S. Quebec, including about 110,000 customers in the Montreal area.

Footage was taken in SW Pierrefonds, located in Montreal's West Island.

~Trav.~