Severe thunderstorms threaten southern Quebec, storm potential for Ontario
Conditions are favourable for the development of severe thunderstorms capable of producing strong wind gusts, large hail and heavy rain this afternoon and this evening in southern regions of Quebec.
9:51 AM EDT
A severe thunderstorm watch is in effect for regions of southern Quebec, including Montreal and Quebec area. Severe thunderstorm watches are issued when atmospheric conditions are favourable for the development of thunderstorms that could produce one or more of the following: large hail, damaging winds, torrential rainfall.
Severe weather marked the start of the week in Ontario, with a tornado warning in northern sections and damaging 100 km/h winds reported in the southwest on Monday. The storm threat will redevelop farther east once again on Tuesday for eastern sections and Quebec. More on the storm impacts and the brief taste of autumn ahead of the Labour Day long weekend, below.
READ MORE: PHOTOS: Wild storms with ferocious 100 km/h winds sweep through Ontario
Tuesday: Early-week thunderstorm threat amid amplified jet stream pattern
An amplified jet stream pattern is set to bring dramatic temperature swings to Ontario and Quebec this week, as we go from summer-like heat and humidity to a hint of autumn. The same system helping to usher in the cooler air is also sparking a widespread thunderstorm risk across the region through Tuesday.
Monday evening saw wicked storms across northern and southern sections of Ontario, downing trees and hydro poles in parts of the southwest with 100 km/h winds recorded in Windsor and Sarnia.
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The storm threat will shift further east on Tuesday, as instability builds over eastern Ontario and Quebec while cooler air filters into the Great Lakes.
The greatest threat for severe storms Tuesday afternoon will be confined to eastern Ontario, southern Quebec and the Niagara region, with torrential rains, strong wind gusts and large hail.
Look ahead: Cooler start to September, but warming up for Labour Day weekend
Only one day in the month of August was below seasonal. There will be a significant shift in this temperature trend during the first few days of September, which are expected to be on the cooler side.
Forecasters will be watching the risk for the chilly weather in northern sections to push farther south. By Thursday, an anomalously chilly lobe of air presses south across northern Ontario, dipping temperatures upwards of 10°C below seasonal for early September near the Ontario and Quebec border.
It’s likely that some communities will have daytime highs stubbornly stuck in the mid-to-upper teens, but farther south down the Highway 401 corridor, the low 20s will be more probable. The taste of early fall is short-lived, though.
Beyond, warmer weather will return during the Labour Day long weekend and continue into the following week for back to school.
Thumbnail image courtesy of Paul Arnold, taken in Hamilton, Ont. Be sure to check back for the latest weather updates for Ontario.