Severe thunderstorm warnings, tornado watches possible amid high risk of storms in Ontario, Quebec

Watch alerts for severe thunderstorms and tornados are in effect across Ontario and Quebec, sparking concerns of major weather to come.

It began with a thunderstorm alert issued shortly before 5 a.m. EDT Thursday for southwestern and central Quebec, but has since expanded as far west as the northern Ontario region of Manitouwadge-Hornepayne, near Lake Superior, and as far south as Wellington County, Ont., east to Hawkesbury, Ont., near Montreal and up to north of Mistissini, Que., evolving into a mixture of watch alerts for severe thunderstorms and the tornados they are known to bring with them.

For more information, seek out local severe weather advisories for your area on Environment Canada's website.

The Environment Canada notice warns that "conditions are favourable for the development of dangerous thunderstorms capable of producing very strong wind gusts, damaging hail and heavy rain this afternoon and this evening."

At present, major cities including Toronto, Ottawa, Montreal and Quebec City remain just outside the boundaries of alerts, though CTV Your Morning meteorologist Kelsey McEwen notes that risk of severe storms could extend beyond their current area.

Among the potential impacts are hot and humid temperatures, feeling like up to 33 C, with possible wind gusts of up to 110 km/h, hail three centimetres in diameter (described by Environment Canada as "nickel to toonie size") and tornados in some regions.

The federal government alert notes that severe thunderstorms are liable to bring tornados, and goes on to advise against water-related activities due to the risk of "violent and sudden gusts of wind," as well as lightning strikes.

Residents in affected areas are advised to go to the lowest floor of their home, away from external walls and windows. Temporary, freestanding shelter such as tents, mobile homes or vehicles should be avoided, in favour of sturdier structures. As a last resort, those without immediate access to shelter should lie in a low spot and protect their head from flying debris.

"Remember, when thunder roars, go indoors!" it reads.

Currently, there is one notice rising to the level of a severe weather warning, the most urgent kind of alert, in Manitouwadge-Hornepayne region, Ont. Environment Canada notes that in the event of thunderstorms and tornados, warnings "can occur rapidly, with less than a half hour’s notice."

Storms are expected to be intermittent as they move through the Great Lakes region, and may affect Toronto and Montreal later in the day, though with comparatively less risk. They may reach Atlantic Canada by Friday, McEwen notes.

This is a developing story. More to come.