In Canada, tornado warnings often come too late or not at all

Last year, the Northern Tornadoes Project — a team of scientists who track tornadoes at Western University — released the first public report card for Canada’s tornado warning system.

The assessment is made possible with thorough accounting of the country’s tornadoes, the main mission of the project. The researchers were able to compare how successfully Environment and Climate Change Canada issued tornado warnings, using this more complete database.

When the team analyzed the system’s performance between 2019 and 2021 using the department’s own targets, the results were dismal.

Environment Canada aims to issue warnings for at least half of all tornadoes, but only got there for 26 percent. The goal is to issue warnings with a run-up time of 10 minutes or more for at least 60 percent of tornadoes, but succeeded only 9.5 percent of the time.

“Actually, it was a failing,” said David Sills, executive director of the Northern Tornadoes Project. More than 70 percent of the storms had no warning, and “a large number of them were not only weak, but also strong EF2s. That was a bit disappointing.”

The team made a number of recommendations, including simply issuing more warnings. Sills, a former Environment Canada researcher, says he knows forecasters worry that false alarms will drive the public off. But he says the literature doesn’t support this: The public is much more concerned about not being given advance notice of an approaching tornado.

“That’s the big concern,” says Sills. “We have too many stories from when we got to the scene, and they say, well, we got the warning after the damage happened. That’s not good enough.”

When Sills and his colleagues released another report for the 2022 tornado season, they found that Environment Canada had doubled warnings and warnings and significantly improved scores. However, they were still very shy of their own goals. The fraction of documented tornadoes that issued a warning was up to 35 percent. The fraction with a warning turnaround time of 10 minutes was 20 percent.

A spokesperson for Environment and Climate Change Canada said the department is aware of the two assessments.

“While this type of analysis is important in increasing the understanding and ability to predict tornadoes, the National Tornadoes Project’s assessment methodology is somewhat limited and does not take into account the breadth of ECCC’s warnings to the public regarding the possibility of bad weather,” Nicole told Allen.

“In addition to tornado warnings and warnings, severe thunderstorm warnings, for example, also give Canadians advance notice of the possibility of tornadoes.”

However, Allen added that Environment Canada is considering the latest report from the Northern Tornadoes Project, along with feedback from emergency management partners, as it plans changes to its storm forecast centers. The department is also completing installation of new, upgraded Doppler weather radars across the country.

The importance of tornado warnings was highlighted by the violent EF-4 tornado that touched down in Alberta on Canada Day, only the second with that rating in Canadian history.

A resident of the area, Elisa Humphreys, told The Canadian Press she was still wearing her pajamas when she got the report. She looked outside, saw a tornado, immediately jumped into her car and drove off. When Humphreys looked back, her property was “shredded” by the twister.

Twelve houses were destroyed or damaged and one person had to be pulled from the basement, but no one was killed.

Kate Allen is a Toronto-based reporter covering climate change for the Star. Follow her on Twitter: @catecallen

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