ONTARIO: Thunderstorm Forecast for Saturday, August 12, 2023

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As we gear up for the weekend across Southern Ontario, we're keeping a close watch on a rather strong severe weather threat. Unlike recent occurrences which centred around Deep Southwestern Ontario or the Ottawa Valley, this time the spotlight is shifting to the GTA, Niagara, and Kingston regions.

We expect to see an intense atmospheric setup extending from the Lake Erie shoreline up into Central Ontario around Lake Simcoe. This dynamic environment is expected to extend eastward, covering the Golden Horseshoe and areas along the Lake Ontario shoreline.

Given the environment, it's likely that any storms forming within this zone could quickly turn severe. The main concern here is the potential for destructive wind gusts, possibly reaching up to 110 km/h. There's also a chance we could see some sizable hail, even up to the size of ping-pong balls.



Now, let's talk tornadoes. The risk is certainly present, particularly around Lake Ontario, which includes the GTA, Niagara, and Kingston regions. While the possibility of an isolated tornado can't be ruled out in most of Southern Ontario, it's more uncertain outside the 'one or two tornadoes' zone.

Now, about timing. Pinpointing the exact starting point of these storms is a bit tricky right now. The latest models suggest scattered storm development across Southern Ontario beginning early Saturday afternoon. We might even see some stronger storms early in the morning, though severe potential might be lower at that time.

For areas in the west, like London, Kitchener, and Barrie, the primary storm risk will likely be during the early afternoon, contingent on where these storms kick-off. The GTA and Niagara region might experience the storm threat lingering into the mid to late afternoon, possibly arriving in multiple rounds. Expect the storm activity to shift eastward as the day progresses, with Kingston in the spotlight around 3 - 6 PM. The severity will ease by evening, dissipating shortly after dinner.



It's worth noting that while we have every part of Southern Ontario at some level of severe risk, most areas may not experience storms at all on Saturday. These storms will be highly localized, impacting only a small area. But within this confined zone, they could pack quite a punch. In Deep Southwestern Ontario and the Ottawa Valley, the potential for severe weather is somewhat lower, falling into the isolated to slight severe threat category.

As always, we're staying on top of the latest data, ready to adjust this forecast as needed. Stay tuned for updates, either later tonight or early tomorrow, to stay informed on the very latest. Your safety matters and is our priority!