Friday, May 04, 2018

Heavy thunderstorms & strong winds forecast for Montreal

A strong cold front will produce severe thunderstorms for portions of southern Quebec and Ontario today. (AccuWeather)
Wind warning posted for metro Montreal.

A potent low pressure system will slide from the upper Great Lakes into western Quebec today. The associated cold front will sweep across Southern Quebec late Friday afternoon. Ahead of this front a few breaks of sun and warming temperatures to near 20C (68F), will act to destabilize the atmosphere. The front will arrive mid to late afternoon, accompanied by a line of heavy showers and thunderstorms. The possibility exists for several of the storms to become severe in eastern Ontario and extreme southern Quebec. Strong winds, hail and heavy rain will be the biggest threat. There is even a slight risk of an isolated tornado, especially south of the St. Lawrence River towards the US border, and into New England.

The temperature will warm in advance of the front, reaching 18 to 21C (65-70F) across the area. As the front clears Montreal, very strong winds will develop in its wake. Wind warnings are in effect for the St. Lawrence Valley, with peak gusts as high as 90km/h possible. The wind will slowly diminish overnight to under 50km/h. On Saturday, we should have clearing skies, along with mild high temperatures of 18C (65F). The wind will remain gusty from the west up to 50km/h.

Water levels continue to slowly rise across Quebec in response to recent rainfall and melting snow. Regions south and east of metro Montreal, including Lake Champlain and the Richelieu River Valley are under flood warnings. A flood watch remains in effect for the rivers surrounding Laval as well as Lac Des Deux-Montagne. According to Hydro Meteo, minor flooding is forecast over the next few days. Vigilance is advised near all bodies of water as they are flowing high, fast and very cold. Minor flooding is also forecast in the Quebec City region, the Mauricie, Lanaudiere, Laurentians and Chaudiere-Appalaches.

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