Wed Sep 21 2022 UTC Day 1 Other Outlook

...Ontario/Quebec...
A broken line of severe thunderstorms developed across portions of Northeastern Ontario this morning spanning from Lake Superior to the Quebec border.

As of 14z (10am ET, local time), these thunderstorms are still ongoing and severe as they pass through parts of South-Central Quebec, east of the Ontario border. These thunderstorms, capable of producing hail to 2cm and wind gusts to 100km/h, will continue east-northeast until they weaken closer to noon or into the early afternoon.

At the same time, (14z, 10 ET), a line of severe thunderstorms has developed in Southern Michigan and is progressing eastward towards Lake Huron and the western shorelines in Ontario. These thunderstorms will likely be severe with hail up to 4cm (ping pong ball) and damaging winds approaching or surpassing 100km/h. A brief tornado cannot be ruled out as the line of storms moves inland.

These existing storms will progress east-southeast throughout the remainder of the morning and extend into the afternoon hours, potentially remaining strong to severe for the entire duration. In particular, the storms in Southwestern Ontario may progress through most or all of Southern Ontario until Lake Erie and Lake Ontario where it will cross back into the United States.

Alongside these existing thunderstorms, the environment will be capable of developing more thunderstorms, both extending from these current storm lines but also with new development ahead and behind the thunderstorm lines. The most likely scenario amongst weather models will be thunderstorms developing ahead of this current line of storms and also extending this current line of storms, creating a broken squall line.

This risk extends to all of Southern Ontario including parts of Southern Quebec.

The main hazards include hail approaching 4cm (ping pong ball-sized), wind gusts reaching up to or surpassing 100km/h, and the threat of a brief tornado or two. The tornado risk is greatest is Southwestern Ontario near Lake Erie and Lake Ontario, however, a broad risk does exist across a much larger region of Southern Ontario, including parts of Central and Eastern Ontario.