Severe Thunderstorms

5pm Update: Waves of thunderstorms have been sweeping across the St. Lawrence and Ottawa Valley's this afternoon. Torrential rain and strong winds have been very common with these storms. Winds gusted over 60m/h at 4pm at Dorval and even higher elsewhere on the island. More storms are developing to our northwest and the threat for severe weather will continue until at least sunset.

3pm Update: This is an update to 3pm. This band of storms will approach Montreal by 4pm.

Maxville - Alexandria
2:29 PM EDT Wednesday 04 August 2010
Severe thunderstorm warning for
Maxville - Alexandria issued

A severe thunderstorm west of Perth will move eastward with the potential to give wind gusts to 90 km/h and heavy downpours. The storm is moving eastward at 50 km/h. Another severe thunderstorm near Rockland will continue eastward to the Québec border and possibly move through Alexandria over the next hour with very heavy downpours and the potential to give 90 km/h gusts. Thunderstorms will develop early this afternoon and may rapidly become severe due to heavy downpours and strong winds. Small hail and frequent lightning is possible and there is a risk of a tornado in the regions under a severe thunderstorm watch.

2pm Update: Thunderstorms continue to increase across the area with a few cells just off the western tip of the island. No warnings have been posted at this time, however watches now cover all of eastern Ontario and southwest Quebec. Flood watches and warnings have been dropped in New England and New York state, however many rivers remain at bank full across Clinton and Franklin counties in New York.

Previous Report: The update below is from Environment Canada. At this time the only storms on radar are northwest of Ottawa. Storms will begin to increase in aerial coverage this afternoon across the region. Flood watches have been upgraded to flood warnings for Clinton County, NY. Some roads have been closed.

Metro Montréal - Laval
11:34 AM EDT Wednesday 04 August 2010
Severe Thunderstorm Watch for
Metro Montréal - Laval issued

Weather conditions in these regions are favourable to the development of severe thunderstorms. Some of these thunderstorms could produce large hailstones, high winds, heavy rain and intense lightning. People in these regions should take the necessary precautions and listen for subsequent weather warnings, as severe weather warnings may be issued if severe weather becomes imminent.

This watch is in effect from 11:30 AM to 07:30 PM EDT.

A major low pressure system over Extreme Northern Québec is producing a trough that extends over the south of the province. Severe thunderstorms could develop along this trough this afternoon.