Potential Severe Storm Risk on Saturday for Greater Toronto Area & Southwestern Ontario
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After the first prolonged heatwave of the season in Ontario this past week, some relief is in sight just in time for the weekend. While the heat warnings for much of Southern Ontario have ended, they continue for one more day in Southwestern Ontario.
Unfortunately, the milder air will be accompanied by active weather throughout the weekend, including the risk of severe thunderstorms in the south and significant rainfall for the northern parts of the region.
thunderstorm risk checklist
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There is a slight risk for severe storms beginning early Saturday afternoon and continuing into the evening hours. This includes areas east of Lake Huron, extending into parts of the Greater Toronto Area.
The main threats will be damaging wind gusts approaching 90-100 km/h and marginally severe hail. Based on the expected environment, we may also see an isolated tornado, although the overall tornado risk is on the lower side.
Storms are expected to pop up somewhere along the corridor stretching from Lake Simcoe southwest into Orangeville and Kitchener-Waterloo starting around 1 to 3 PM. Additional storm development may occur over Lake Huron and track onshore between Wiarton and Grand Bend throughout the afternoon.
Current indications suggest that any storms developing today will move slowly, which means flooding could be a big concern, especially if they reach the more urban areas around the Golden Horseshoe and begin to ‘train’ over a specific location.
Any of these storms will have the potential to bring severe weather, including wind gusts and hail. The tornado threat is highest earlier in the day to the northwest of the GTA, including Grey, Bruce, Wellington, Dufferin and Simcoe counties.
The storm threat will diminish by early evening as the sun sets and the daylight heating fueling the storm activity shuts off. However, non-severe thunderstorms will remain possible overnight into Sunday morning, especially for Eastern Ontario.
Further north, heavy rain will move across Central and Northeastern Ontario, with embedded pockets of non-severe thunderstorm activity starting this afternoon. Eastern Ontario will begin to experience rain by late evening. This is expected to continue through the overnight hours and into Sunday, with substantial rainfall totals approaching 100mm by the end of the weekend.
Environment Canada has issued a rainfall warning for the affected region. We will have a more detailed update on the significant rainfall in a separate forecast later today.
