Alberta had a slow tornado season. That wasn't the case elsewhere in Canada

The Prairies Climate Change Project is a joint initiative between CBC Edmonton and CBC Saskatchewan that focuses on weather and our changing climate. Meteorologist Christy Climenhaga brings her expert voice to the conversation to help explain weather phenomena and climate change and how it impacts everyday life.

Fall is well underway and with that, an end to tornado season in Canada. 

This year's tornado season has stood apart from last year's sleepy summer for supercell thunderstorms, but in Alberta, tornado numbers are still relatively low.

"We did have eight tornadoes, and last year only three, but both of those are quite a bit lower than normal," says Kyle Fougere, a warning preparedness meteorologist with Environment and Climate Change Canada.

Looking at climatology between 1980 and 2009, Alberta averaged 15 tornadoes a year, Fougere says. Those climate numbers are updated for the latest 30-year window, with the 1990 to 2020 numbers expected next year.

But 2022 wasn't a slow year everywhere in Canada. Saskatchewan saw its busiest summer for tornadoes in a decade, with 25 confirmed. The historical average for Saskatchewan is closer to 18 tornadoes over the summer.

"It's actually the most tornadoes we've had in Saskatchewan since 2012, when they recorded 33 tornadoes," Fougere says.

So why the drastic difference between neighbouring provinces? And how are the numbers of tornadoes we see in a typical year shifting over time?

Alberta's low count has been a trend over the past decade. Fougere says the only time we saw more than 15 tornadoes in a season was in 2019, when there were 23.

But as we saw this summer in Saskatchewan, there hasn't been a tornado drought everywhere.

"Every year we do see a lot of variability in tornado numbers," says Fougere. "It's not that rare to see one province have a much different summer than the province next to it."

Early season landspout tornadoes, which are weaker and can form without strong thunderstorms, can drive up numbers.

Large-scale setups in the atmosphere — such as expansive areas of high pressure, or persistent patterns in the jet stream — also play a role, as was the case this year.

"We had a big ridge of high pressure from about the second week of July onward … over Western Canada," Fougere says.