Southern Ontario: Thunderstorm Outlook for Friday, June 18, 2021

Forecast Discussion

A cluster of thunderstorms is expected to track across Southern Ontario during the morning hours on Friday with the highest chance for a thunderstorm around the Georgian Bay shoreline. These morning storms should remain non-severe although they could pose a localized flooding risk especially since many areas haven’t seen a lot of rainfall over the past few weeks.

The main story will be later in the day where there is an isolated severe risk during the afternoon and evening through parts of Southwestern Ontario around the Lake Erie shoreline. Storms are very likely to develop, but it’s unclear exactly where these storms develop. It’s possible we see them develop over Lake Erie and track stateside which would pose very little risk to the region. If they develop over Southwestern Ontario then we could see some damaging wind gusts, large hail and heavy rainfall from these storms around the Lake Erie shoreline and into the Windsor area.

Further north around Lake Simcoe and the GTA, there is a questionable severe risk if storms are able to develop early enough in the evening to take advantage of the environment which is looking unlikely at this point. As for the tornado risk, it appears the strongest tornado risk will remain south of the border although it can’t be fully ruled out if we get an isolated discreet storm that pops up in the prime environment.

Some storm development is possible overnight into Saturday however any storms that develop should be non-severe after sunset.