ONTARIO: Thunderstorm Forecast for Thursday, August 10, 2023

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Prepare for a resurgence of thunderstorm activity across Southern Ontario on Thursday. This will be accompanied by an isolated severe threat spanning from Southwestern Ontario through the Golden Horseshoe and extending into Eastern Ontario. Our attention is focused on two distinct areas of storm development in Southern Ontario.

Firstly, storms are anticipated to originate over Lake Huron, tracking into the Greater Toronto Area (GTA) and Niagara region. Simultaneously, another zone of storm development is anticipated, ranging from Lake Simcoe up to Renfrew. These storms are projected to commence during the early afternoon hours and advance eastward throughout the day.

While these storms are not expected to be widespread, they possess the potential to reach marginally severe levels, accompanied by wind gusts of up to 90 km/h, hail reaching the size of quarters, and substantial rainfall. Additionally, there exists a chance of isolated tornado activity.

The precise timing of these storm formations introduces an element of uncertainty that could influence the overall storm threat. Delayed storm initiation would elevate the severity threat, as increased daylight heating would contribute to heightened energy levels. Conversely, some models indicate the potential for initiation further east, possibly even outside of Ontario.

Currently, we are sticking with an isolated severe threat. It is crucial to note that not all regions within the severe risk area will experience storm activity on Thursday. Any storm occurrence will be localized, impacting a limited area.

In our upcoming Wednesday evening update, we might consider introducing a more localized 'slight' severe risk zone if the environmental conditions indicate a stronger potential than initially anticipated.