2017 Quebec tornado cluster among largest recorded in Canada, researchers say

A cluster of tornadoes that knocked down trees and tore the roof off a home in southern Quebec last June was one of the largest ever recorded in Canada, according to new research from Western University.

The findings suggest the extreme storms are more common in the country than previously thought.

As part of a pilot project to detect previously unreported tornadoes, Western researchers found that a record-setting 11 tornadoes touched down in Quebec on June 18, 2017, rather than the four that were previously recorded.

That's the most ever recorded in the province.

To reach their conclusion, the team used aircraft to fly over areas that had produced weather ''super-cells,'' then worked backwards using images of the damage to estimate the wind speeds, according to an engineering professor who worked on the study.

"Basically, we think that the tree-fall pattern — the proportion of trees that go down and also the patterns of the trees — gives us an indication of how strong the tornado will have been," Gregory Kopp said in a phone interview.

Kopp said the most powerful tornado to hit southern Quebec that day was a 200 km/h twister that damaged a 30-kilometre swath near Ste-Anne-du-Lac, north of Montreal.

"There was a house there that was completely destroyed, so the roof and the walls were sucked away, all the contents were hundreds of metres downwind," he said.

According to Environment Canada, about 60 tornadoes are observed in Canada each year, most of them in the Prairies and southern Ontario.

But weather models suggest the true number is closer to 200, according to meteorologist Alexandre Parent.

Parent said the federal agency usually depends on reports from observers on the ground in order to confirm a tornado, which means that those in remote areas can be missed.

He said the study suggests tornadoes are much more common in Canada than experts previously believed.

"There are many that last only a few minutes, or that measure only a few dozen or a few hundreds metres wide, so they're touching very, very local sectors," he said.

Because Western's study is new, Parent says it's too soon to say how it could be used in the future.

Kopp, however, believes the added information could help authorities better identify tornadoes as they form, thus improving the effectiveness of the early warning system.

He said it could also lead more builders to adopt tornado-proof building standards, at a cost of only a few hundred dollars more per home.

News of Quebec's record-breaking June tornado cluster came as no surprise to one amateur storm chaser who has travelled across North America in the pursuit of the elusive storms.

Jean-Francois Massicotte said he was looking at weather data that day and saw the most volatile conditions forming in areas that were too hard to chase.

"We were seeing all these big thunderstorms up north that we just couldn't reach, we couldn't get to them, so I'm not surprised that somebody made a study and found there were many more tornadoes on that day," said Massicotte, a member of a group of self-described "weather nerds" that calls itself Quebec Vortex.

Massicotte, 34, says tornadoes move quickly, don't last long and don't always follow the roads, which makes them hard to catch.

But that hasn't stopped him from trying, by using weather models, satellite images, radar, and weather reports and then racing to likely sites in the hopes of getting lucky.

"The most spectacular thing you notice is the clouds, how they're all racing towards the point where it will form," he said.

While he's come close a few times, he says his ultimate goal is to get close enough to get that perfect photo, looking straight up into a powerful storm.