Cluster of strong nocturnal storms targets southwestern Ontario

·4 min read
Cluster of strong nocturnal storms targets southwestern Ontario
Cluster of strong nocturnal storms targets southwestern Ontario

Monday night may not be ideal for sleeping if you're in southwestern Ontario, with forecasters keeping a close eye on a mesoscale convective system (MCS) in the Upper Midwest that has the chance of clipping the region in the overnight hours through the pre-dawn Tuesday morning. These storms, depending on the timing and track, could bring damaging winds, heavy rain and frequent lightning as far north as London. Details on Monday's storm threat, plus a look at the building heat and humidity that follows, below.

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An incoming MSC, or cluster of thunderstorms, may clip the southwestern sections Monday overnight. The MCS threat in Canada depends on the track of a disturbance as it rounds the ridge of high pressure responsible for extreme heat across much of the continental U.S.


The cluster of storms are forecast to track towards extreme southwestern Ontario through pre-dawn Tuesday as an active storm boundary on the northern periphery of the southern U.S. heat dome slowly inches northeast.

There is still some uncertainty, however, with how much of southwestern Ontario, if any, will be impacted by these storms.

"The greatest confidence for impacted areas looks to be from Sarnia to Windsor, but the threat for some thunderstorms may push as far north as London and to Hamilton through the pre-dawn hours on Tuesday," Sonnenburg adds.

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Mainly sunny skies will return for southern Ontario Tuesday, with increasing heat and humidity as a ridge continues to build into the region.

Several days of above-seasonal temperatures are likely through the week, with daytime highs in the upper 20s to near 30 possible in some areas. The humidity will build and parts of southwestern Ontario could see humidex values spill into the 40s by Wednesday.

Easterly winds off Lake Ontario would likely keep the Greater Toronto Area cooler mid-week.


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Thursday will be a hot and humid day with high temperatures ranging from the upper 20s to lower 30s -- approaching the mid-30s for southwestern Ontario -- with the humidex in the upper 30s to mid-40s.

An approaching system on Thursday combined with the sizzling temperatures will spark widespread thunderstorms. With the current set-up, severe thunderstorms will likely be on the table once again.

Cooler but near seasonal for Friday -- a gorgeous day for southern Ontario, but showers and thunderstorms for eastern areas. A beautiful weekend across southern Ontario with abundant sunshine, but temperatures will be a few degrees cooler than seasonal.

A warming trend early and mid-next week as the heat wave over the U.S. Midwest attempts to spread into the region, but then turning cooler late week and weekend.

Stay tuned to The Weather Network for all the latest on conditions across Ontario.

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