Q&A: Researcher confirms two tornadoes in Quebec, predicts stormy summer

The intensity of last Thursday's thunderstorms in the greater Montreal area caught a lot of people by surprise. There were torrential rains, fierce winds and even a tornado in Mirabel.

Experts say climate change likely means we'll see more of the weather conditions that could lead to tornadoes. CTV news anchor Maya Johnson spoke with David Sills, Executive Director of the Northern Tornadoes Project at Western University.

This interview has been edited for clarity and concision.

Q - Let's start with a recap. What has now been confirmed in terms of the number of tornadoes we saw touchdown last week in Quebec and Ontario?

A - After that big line of storms went through Ontario, and Quebec we had survey teams out collecting data. So right now we have the Quebec results all completed as of today. And actually, there were two tornadoes in Quebec. One was that Mirabel tornado which had a default EF zero rating, because there was no damage that was reported with that. But there was also another tornado, EF zero, so lowest on the EF scale at St. Thomas. In addition to that, five downbursts in Sainte-Anne-des-Plaines, Sorel Tracy and Saint-Anicet.

Q - What's the difference between a downburst and a tornado?

A - Now that's a good question! So a simple answer is with a tornado, you've got air coming in towards the storm and up into the tornado area. And with a downburst, you've got air that's rain cooled, that's falling out of the thunderstorm and spreading out and causing damage at the ground.

So you can imagine, because of those different air patterns, you're getting a different damage signature. And that's what we look for when we send teams out to do the damage surveys, is to look for those different damage patterns. One is kind of widespread damage, usually fairly weak, whereas the other tornado damage will be a long narrow path and can be much, much stronger.

Q - Can you put all of this into perspective for us? Are we seeing more tornadoes and downbursts? Or do we not have enough reliable data yet to draw that conclusion?

A - There are some modeling studies that suggest that in the future, there may be less tornadoes in the West, more in the East. And you know, our observations with the northern tornadoes project since 2017, have supported that idea. There have been a lot of tornadoes in Eastern Ontario and southern Quebec, and not as many as we expected on the prairies. As far as the number of tornadoes increasing, we have to collect a lot more data to see if those climate models are panning out.

Q - Do you think we'll be seeing more of this in the future? Is it hard to say right now?

A - Well, this is actually peak season across Canada, July is the month for tornadoes and basically all severe storm activity across the country. So we're right in the thick of it. We'll probably have lots of storms and the chance for more tornadoes and downbursts. Hopefully, nothing really devastating. Right into August and maybe the beginning of September and then it all starts to wind down.