Move over Kansas, Quebec saw record-breaking 11 tornadoes in a single day last summer

A total of 11 tornadoes touched down in southern Quebec in one day last year, June 18, 2017 — the most ever recorded in the province's history.

Researchers at Western University track and identify previously unreported tornadoes

The tornado that hit the Saguenay region on Lac Kénogami was one of 11 that affected the Southern Quebec area on June 18, 2017. (Peter Rodgers/Facebook)

A total of 11 tornadoes touched down in southern Quebec in a single day last year — the most ever recorded in the province's history.

The stormy weather hit on June 18, 2017. Environment Canada originally confirmed at the time that three tornadoes and a microburst had affected communities across the region, but researchers at Western University in London, Ont., took a second look.

After an extensive ground and aerial survey led by wind engineering experts, the team was able to confirm the confluence of separate tornadoes.

"We identified several tornadoes that hadn't been recorded," said Greg Kopp, a professor of engineering who helped lead the project.

Kopp identifies tornadoes that go unreported, often because they happen in areas that aren't populated.

He told CBC that usually on average, Quebec has about 10 recorded tornadoes per year, so seeing that many in a single day is highly unusual.

A chalet was destroyed by the heavy winds in Lac-Saint-Jean on June 18, 2017. (Mélanie Patry/Radio-Canada)

"This is the fifth largest in Canadian history, so it's a really significant event."

On that day, a number of supercell thunderstorms developed, producing hail, strong winds and tornadoes.

There was extensive property damage and some houses were destroyed.

The team from Western University conducted several ground surveys and analyzed satellite images to track the paths of these intense weather systems.

A residence in Hébertville, Que., was destroyed by strong winds during the tornado. (Radio-Canada)

The tornadoes carved paths several kilometres long in the Lac-Saint-Jean and the Mont-Laurier regions, as well as the Laurentides Wildlife Reserve between Quebec City and Saguenay.

The highest rating of the day was measured over Sainte-Anne-du-Lac in the Laurentians, hitting a Class 3 on the Enhanced Fujita scale, which rates the intensity of tornadoes using a five-point scale. That storm drew winds of up to 250 kilometres per hour.

In a densely populated place like Montreal or Quebec City, the same EF-3 tornado could do a lot more damage, said Kopp.

"We need to have a real understanding of the risk," he said.

That's part of the reason why the team is making an effort to get a clearer picture of the "real numbers." Kopp said the team hopes to build a representative picture of just how many tornadoes go unreported in Canada every year.

With files from CBC Homerun