Isolated Severe Thunderstorms Could Impact Victoria Day Celebrations in Southern Ontario
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Southern Ontario has enjoyed stellar weather conditions throughout the long weekend, with temperatures reaching 30°C in some locations on Sunday! However, it looks like this hot weather will cause the long weekend to end with a bang—and not the kind of bang you see with fireworks.
The hot, humid air across Southern Ontario will provide the perfect fuel for isolated pop-up storms to develop later on Monday afternoon and continue into the evening. Although these storms will be small and very isolated, they could still pack a punch with up to quarter-sized hail, 90 km/h wind gusts, and potential flooding due to their slow-moving nature.
The primary risk for this storm activity is around the Lake Simcoe shoreline and southwest near Lake Huron. It’s important to note that not everyone will experience a storm today, and there’s a good chance that most areas will remain dry. If you do encounter a storm, it could certainly have the potential to bring severe weather.
At this point, the tornado threat is relatively low, but a brief spin-up or even a landspout (non-supercell) tornado can't be ruled out with these pulse storms. The pop-up storm threat will diminish after sunset as the daylight heating fueling these storms disappears.
In addition to the severe threat during the day, we are closely monitoring the expected arrival of a decaying line of storms from Michigan overnight. This should be mostly non-severe as it crosses over Lake Huron and Georgian Bay early Tuesday morning. However, we may see some marginally severe wind gusts and perhaps some small hail as it tracks through Central Ontario and into Eastern Ontario by late morning.
Tuesday morning's convection will be crucial for setting the stage for a potentially severe threat later on in the afternoon. Current indications suggest a fairly potent environment across parts of Eastern Ontario, especially the Ottawa Valley and along the Quebec border.
If storms develop, we could see the risk of large hail, damaging wind gusts, and maybe even one or two tornadoes. It’s currently looking like a slight (level 2) risk, but we may have to introduce a localized strong (level 3) risk zone if models increase in intensity. A full forecast will be issued later today or early tomorrow.
Wednesday continues to appear as the most intense day for potential severe weather this week, with almost all of Southern Ontario potentially in the bullseye. However, it’s unclear if storms will actually be able to develop and take advantage of the prime environment over Southern Ontario. We will continue to monitor the situation and provide more details soon.
