ONTARIO: Thunderstorm Forecast for Tuesday, July 11, 2023
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FORECAST DISCUSSION
A widespread risk of thunderstorms is expected across Southern Ontario on Tuesday. This includes a slight risk of severe storms along the Lake Huron shoreline and into the Collingwood/Barrie region during the mid to late afternoon hours. Storm development is anticipated after the lunch hour, with isolated storms originating from Lake Huron and tracking into Southwestern and Central Ontario.
The primary concern lies along the Kincardine, Collingwood, and Barrie corridor. As these storms move through the region, there is a potential for a brief tornado. Large hail and strong wind gusts are also possible with these storms.
Further south, strong storm development is expected over Lake Huron in the mid-afternoon (2-4 PM) as they make landfall from Sarnia through Grand Bend and into Goderich. The environment these storms will encounter has the potential for significant hail, up to the size of toonies or even golf balls, along with wind gusts of 100 km/h. There is also a tornado risk, particularly as these storms reach their peak strength upon landfall.
By the later afternoon, the previously isolated storms are expected to merge into a long line of storms extending from Barrie southward to London. This line will primarily bring a threat of damaging wind gusts ranging from 90-100 km/h, with quarter-sized hail and a risk of flash flooding. Isolated pop-up storms are also possible throughout Central Ontario and into the Ottawa Valley, although no organized activity is expected. These storms could still produce large hail and damaging wind gusts.
TORNADO RISK
The focus of the tornado risk will be along the Lake Huron and southern Georgian Bay shorelines. Given the environment and timing, there is a decent chance of seeing at least one tornado somewhere in the Sarnia, Grand Bend, Goderich, and Kincardine region. Timing is crucial, as these events have previously started earlier than expected before daylight heating fully primes the environment for maximum severe potential.
An isolated tornado risk extends from southwestern Ontario through much of Central Ontario and into the Ottawa Valley. While the Golden Horseshoe may experience marginally severe storms, the line of storms is expected to have less energy upon reaching the area. Therefore, the primary threat will be damaging winds, with minimal risk of tornadoes.
