Southern Ontario: Thunderstorm Outlook for Thursday, July 15, 2021

Forecast Discussion

Forecast Update: Good afternoon! We’ve reviewed the latest data this morning and we believe our map from last night still accurately depicts the risk for this afternoon and evening. Already have some non-severe thunderstorms development through Central Ontario ahead of the main event that’s expected to get going in a few hours. Concerned about the potential for one or two tornadoes through the Simcoe County, Kawartha Lakes, Muskoka, Haliburton region and up into Algonquin Park/Pembroke. Models consistently have a bullseye around this region and at the very least we can expect damaging wind gusts and large hail. The rest of the region is at risk for some widespread wind damage from a squall line that could develop late this afternoon. It will continue eastward into the early evening. We’ll keep you covered all day today with storm updates and our live stream which should be starting soon.

Original Forecast:

After many locations are just beginning to clean up from Tuesday’s storms the sweep across parts of Southern Ontario, there’s the potential for more strong severe storms during the afternoon and evening on Thursday. The areas at the highest risk of these storms include much of the same areas hit hard on Tuesday stretching from Lake Huron to the northeast through Lake Simcoe and into Central Ontario. Storms are expected to develop during the early afternoon and could pose a strong wind gust, large hail and tornado risk early in their lifespan. Current data indicates the strongest tornado threat exists through the Orangeville-Barrie-Muskoka corridor during the afternoon.

Later in the day, it appears that the isolated storms will slowly merge into one main squall line with the main risk turning towards widespread 90-100km/h damaging wind gusts. This line will track to the east and southeast reaching the GTA by the dinner hour or early evening. It will slowly weaken through the evening and should no longer pose a severe threat by the time it reaches Extreme Eastern Ontario. There is also some potential for a few isolated severe storms that may track into Deep Southwestern Ontario (Windsor, Chatham-Kent etc.) during the evening. The main risk with these storms will be strong wind gusts.

The severe risk will come to an end by the late evening although a few non-severe storms may linger past the midnight hour.