Severe Storm Threat Returns to Southern Ontario on Friday to Kick Off the First Weekend of July
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The first few days of July have started off quietly, in stark contrast to June, which saw multiple rounds of severe weather across Southern Ontario. However, it seems that change is on the horizon with the return of storm threats to parts of the region on Friday.
There is a slight (level 2) severe risk across a wide swath of Central and Southwestern Ontario, stretching from the Lake Huron shoreline through Lake Simcoe, into Muskoka, and up to Algonquin Park. A marginal (level 1) severe threat extends from Deep Southwestern Ontario through the Golden Horseshoe into Eastern Ontario.
Storms are expected to develop sometime during the early to mid-afternoon hours along a line stretching from Sudbury to London. There is some disagreement among models regarding the exact timing of storm development, with some suggesting later in the day. If these early afternoon storms materialize, they will track northeastward throughout the afternoon toward Lake Simcoe and Central Ontario.
thunderstorm risk checklist
Given the atmospheric conditions, a few of these storms could pose severe threats, including damaging wind gusts, hail up to the size of toonies, and an isolated tornado cannot be ruled out. Additionally, isolated storms may develop across Muskoka and into the Algonquin Park region, presenting similar severe threats.
In areas outside of Central Ontario, such as Southwestern Ontario and the Golden Horseshoe, there is a possibility of isolated storms during the afternoon and early evening. However, confidence in this scenario is lower.
Any storms that do form are expected to be extremely isolated and less widespread compared to the ‘slight’ risk zone, thus warranting a ‘marginal’ (level 1) risk level for this region.
By the evening, attention will shift toward the Quebec border from Pembroke to the Ottawa Valley, including Eastern Ontario. Some models suggest that the cluster of storms over Central Ontario could maintain strength as it moves into this area. However, it remains uncertain if these storms will sustain intensity as we approach sunset around 8-9 PM and lose daytime heating.
All storm activity is expected to diminish across Southern Ontario by midnight. Nonetheless, isolated pop-up storms may occur in northern parts of Southern Ontario and the Ottawa Valley early Saturday morning. While these storms are anticipated to be non-severe, their slow movement could lead to localized flooding.
We are also closely monitoring another potential round of storms during Saturday afternoon and evening. Currently, the focus for these storms appears to be the Ottawa Valley along the Quebec border. Some of these storms could reach severe levels, with the latest data indicating a marginal to slight severe risk.
We will provide a detailed forecast for Saturday posted sometime on Friday.
