Northern Ontario: Thunderstorm Outlook for Thursday, September 16, 2021

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Forecast Discussion

Scattered thunderstorms are possible during the day on Thursday through parts of Northwestern Ontario along the International border. A few of these storms particularly during the afternoon and evening could reach severe levels with large hail, strong wind gusts and heavy rainfall. An isolated tornado can’t be ruled out either but it’s very questionable. The storm risk will come to an end later in the evening.

Southern Ontario: Thunderstorm Outlook for Tuesday, September 14, 2021

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Forecast Discussion

What appears to be a regular occurrence in Southern Ontario on Tuesdays, we’re expecting the potential for very strong storms during the afternoon and evening. This will begin with a line of storms stretching from Lake Huron across Georgian Bay and into Central Ontario during the mid to late afternoon. The line will slowly progress to the southeast during the remainder of the afternoon and into the evening reaching the GTA by the early evening and Eastern Ontario later in the evening. We can expect these storms to bring the threat of large hail, damaging wind gusts, frequent lightning and heavy rainfall. There is also a fairly strong chance of tornadoes with this setup. As shown on the map, we believe the area with the strongest threat from these storms includes regions east of Lake Huron and Georgian Bay with the severe threat diminishing later in the day as the storms track to the east.

Southern Ontario: Thunderstorm Outlook for Monday, September 13, 2021

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Forecast Discussion

Pop-up thunderstorms are possible across Southwestern Ontario and into the Niagara region on Monday. They should remain predominantly non-severe with strong wind gusts, small hail and heavy downpours. It’s not out of the question that we see an isolated severe storm mainly due to the heavy rainfall potential, but it’s not widespread enough to include on the map.

Southern Ontario: Thunderstorm Outlook for Sunday, September 12, 2021

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Forecast Discussion

Scattered thunderstorms are expected to develop across parts of Southwestern Ontario and into the Golden Horseshoe during the afternoon and evening on Sunday. The environment is favourable for a few of these storms to reach severe levels with damaging wind gusts as the main threat along with small to medium sized hail and heavy downpours. An isolated tornado can’t be ruled out either, but the risk isn’t particularly strong. The strongest risk zone extends from Southern Lake Huron, through London and along the Northern Lake Erie shoreline. Current weather guidances show strong cells developing over Michigan during the afternoon and track into the Sarnia and Grand Bend area by the late afternoon. It’s should be fairly quiet for those north of Lake Simcoe with the thunderstorm risk contained to the southern part of our region. The storm risk should come to an end by midnight.

Northern Ontario: Thunderstorm Outlook for Saturday, September 11, 2021

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Forecast Discussion

Isolated severe thunderstorms are expected to affect Northeastern Ontario during the afternoon and early evening on Saturday. These storms could bring the threat of damaging wind gusts, large hail and heavy downpours. A few tornadoes can’t be ruled out either along the Quebec border and north of Georgian Bay although the risk isn’t super strong. Storms will move out of the region by the late evening.

Southern Ontario: Thunderstorm Outlook for Saturday, September 11, 2021

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Forecast Discussion

Isolated severe storms are expected to develop through Northeastern Ontario during the afternoon on Saturday. These storms will sink southeastward by the evening and could affect regions around Georgian Bay and Lake Huron. There is some uncertainty regarding timing and the exact severity of these storms, but at this point it appears that some damaging wind gusts can’t be ruled out. The tornado risk isn’t particularly strong with this set up so we haven’t included it on the map but an isolated tornado isn’t out of the question especially for the Bruce Peninsula and up into Northeastern Ontario. The risk will come to an end later in the evening although the non-severe storms could linger into early Sunday morning.

Southern Ontario: Thunderstorm Outlook for Wednesday, September 8, 2021

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Forecast Discussion

A few non-severe thunderstorms are possible Wednesday morning throughout the GTA and into Eastern Ontario. There may also be a few isolated cells later in the day around Georgian Bay and Lake Huron, but they should remain non-severe with small hail, strong wind gusts and heavy rainfall.

Northern Ontario: Thunderstorm Outlook for Tuesday, September 7, 2021

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Forecast Discussion

Scattered thunderstorms are expected through parts of Northern Ontario, but at this point, it appears to be very isolated so an outlook won’t be issued. Stronger storms are possible for areas along the Georgian Bay shoreline which was covered in the Southern Ontario outlook.