Canada Day to bring severe thunderstorm threat to Ontario, Quebec

Canada Day to bring severe thunderstorm threat to Ontario, Quebec

Following some severe thunderstorm threats and tornado warnings on Friday, Ontario and Quebec will face a renewed risk for severe thunderstorms throughout Canada Day on Saturday.

Warm, unstable air parked over the region will allow widespread thunderstorms to grow with the day’s heat. Wind shear could allow the storms to increase from strong to severe, especially in eastern Ontario and southern Quebec.

There is some potential for supercell activity to develop as the heat increases throughout the day.

Keep the radar handy on your phone if you’re under the threat of storms on Saturday, and make a plan to seek shelter in a hurry if hazardous weather approaches your location. If you can hear thunder, you’re close enough to be struck by lightning.

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Saturday

Areas: Ontario and Quebec

Timing: Afternoon and evening

Weather:

EastRisk

The risk for thunderstorms will continue Saturday throughout southern and eastern Ontario, with the threat expanding to include much of Quebec through the day.

Winds wrapping around a low-pressure system will pull a slug of warm, moist air surging into the region. This pool of unstable air will provide ample fuel for thunderstorms to thrive once they get going in the afternoon and evening hours.

The storms will be scattered in nature throughout the afternoon and into the evening as the system rolls through. As the temperature warms throughout the day, there is the potential for some rotation to occur, which increases the risk of supercell activity developing in the area.

ON supercell

The strongest storms could produce large hail, strong wind gusts, and heavy rainfall. One or two tornadoes can’t be ruled out, especially in eastern Ontario and southern Quebec.

Thunderstorms will be more widespread than we saw on Friday, and they’ll be slow-moving, which could lead to localized flooding beneath the heftier storms.

Heat and humidity alone will make the day uncomfortably sticky for anyone spending any length of time outdoors. Humidex values will climb into the low- to mid-30s for southern portions of Ontario and Quebec on Saturday afternoon, with a humidex in the upper 30s possible in far southwestern Ontario.

ON humidity

Sunday

Areas: Ontario and Quebec

Timing: Afternoon and the evening

Weather: Some thunderstorms will continue overnight as the system continues to move towards the northeast.

A second low-pressure system will then track into the province early Sunday morning, bringing more widespread rain into the Greater Toronto Area (GTA) with some embedded thunderstorms and slightly cooler temperatures.

ON risk SUN

Areas in eastern Ontario into Quebec will also see the possibility of another round of severe thunderstorms in the evening.

Looking ahead, precipitation will continue as the threat of thunderstorms ramps up in Ontario as temperatures soar into the low 30s with humidex values nearing the 40s.

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A threat for potent thunderstorms during the afternoon and evening hours on Canada Day is especially tricky given the number of outdoor plans and activities scheduled throughout the region.

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Keep The Weather Network’s app handy on your phone to peek at the radar and keep up with watches and warnings as the day progresses.

Stay close to safe shelter in case storms threaten your location. And remember, the greatest danger in any thunderstorm is lightning. If you can hear thunder, you’re close enough to be struck by lightning.

Thumbnail credit: Pexels/Andre Furtado

Stay with The Weather Network for the latest on the severe storm threat across the region.

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