ONTARIO: Noisy Start to the Last Week of Summer With the Risk of Severe Thunderstorms and Tornadoes on Monday
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It’s the time of the year when summer winds down and we have to start talking about the f-word. No, not that f-word (well not yet that is), but rather it’s the end of August which means fall is almost here! Meteorological autumn actually begins on Thursday as the calendar turns from August to September while the more standard astronomical autumn doesn’t begin for a few more weeks. Although we might be saying goodbye to summer, it doesn’t mean that Mother Nature is quite done with summer-like weather just yet! It certainly doesn’t feel like fall which will continue into Monday as we expect hot and humid temperatures across Southern Ontario. This has prompted Environment Canada to issue Heat Warnings for the Windsor-Essex and Niagara regions with the humidex making it feel into the upper thirties.
As we are all accustomed to, the hot weather also provides the perfect fuel for thunderstorms and that will be the case for Monday afternoon into the evening. This will all begin pre-dawn Monday as some decaying storms move into the region from Michigan. Based on the timing, we aren’t expecting any severe weather for Monday morning and it’s even questionable if we see any lightning. However, it will bring rain and cloud cover to Southern Ontario throughout the morning which will be key in setting the stage for severe storm development later in the day. If the morning rain can clear out early enough, it will allow for enough daylight heating to build and fuel the potential storms for the afternoon and evening. If it lingers around into the afternoon, this will push any development to later in the day when the environment will be less favourable for any storms to become severe.
At this point, we are assuming that the storms clear out early enough so our forecast is based on that. So keep in mind that confidence isn’t super higher and we may need to make adjustments by early Monday afternoon once we see what happens with the morning activity. We are watching two potential regions where storms could develop with the first round of storms popping up around the Collingwood and Hanover area during the mid-afternoon. These isolated cells will track to the northeast towards Lake Simcoe with all severe threats on the table including damaging wind gusts, large hail and even an isolated tornado that can’t be ruled out.
By the dinner hour, we expect to see some storms begin to fire up over Lake Huron and quickly form into a squall line by the early evening. Although there is some disagreement between the models with some showing the line forming over Central Michigan and not reaching our region until later in the evening. Exactly where this line forms will be critical in determining the risk it will pose to Southern Ontario. Should the storms develop over Lake Huron, they will reach the shoreline around 7-9 PM with all severe threats including a tornado possible. The line will slowly to the southeast throughout the evening and transition into more of a damaging wind risk with the hail and tornado risk diminishing further inland. We should see the severe risk come to an end by late evening as the line of storms weaken into non-severe thunderstorms and track into Eastern Ontario overnight.
For those in Eastern Ontario, we are watching the potential risk of severe thunderstorms for Tuesday afternoon and evening. It isn’t looking that widespread at this point, but still could be an issue. We will have more details as we get closer to Tuesday. As we mentioned, this forecast is preliminary and may need to be updated on Monday once we see how the morning precipitation plays out. Stay tuned and check back for the very latest!
IMPORTANT: If storms start developing, we will likely be live-streaming via YouTube, Facebook, Twitter, and Twitch as we track every developing storm and notify those in the path of any rotation, tornado reports, damaging winds, and large hail on our free app Instant Weather and via our premium Text Message Alerts. If you don’t have PayPal, you can also subscribe to our text messages directly on our website, however, the PayPal option is automated so it will work immediately as we may not be able to get to everyone who subscribes via our website due to the fact that we have to enter those in manually.
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