• Gatineau, Que. tornado Sept. 21, 2018

    A tornado touches down in Gatineau, Que. on Sept. 21, 2018. (Photo: Alexandra Pope/Canadian Geographic)

On May 21, 2020, security cameras at a home in Saanich, B.C., north of Victoria, captured video of what appeared to be a weak tornado touching down in a backyard, sending a trampoline flying high into the air. 

For severe weather scientist Dave Sills, the event — likely Canada’s first tornado of 2020 — was a surprising and coincidentally-timed kickoff to a research season like no other. Just hours before, Sills and colleague Greg Kopp from Western University in London, Ont. had held a virtual briefing for media and members of the public about how their Northern Tornadoes Project will continue its research into severe weather events in Canada in light of public health guidelines to slow the spread of COVID-19. 

Normally, a team of trained investigators could be dispatched to the site of a reported tornado to assess the damage on the ground and determine whether a tornado or other wind event such as a downburst occurred. Physical distancing requirements will make that more challenging this year, so crowdsourced reports and images like the home security footage from Saanich will be more important than ever.

“We’re looking for citizen scientists — people who are very interested in weather and tornadoes in particular,” says Sills. “We help them to understand [what they saw], and they help us to understand the bigger picture as far as tornado occurrence across the country.”

The Northern Tornadoes Project began in 2017 as a way to identify tornadoes that occur in sparsely populated areas of Canada. The country sees an average of 61 confirmed tornadoes each year, but experts have long believed that the actual number is much higher. Tornadoes can and have happened in every province, and have even been recorded north of the 60th parallel. The problem, jokes Kopp, is that moose don’t carry cell phones. 

Kopp is a professor in the department of civil and environmental engineering at Western. He’s interested in designing homes and structures that are better able to withstand violent wind events like tornadoes and hurricanes. “To do that, we have to understand what the risks are,” he says. “If we’re missing large numbers of tornadoes, our risk calculations are going to be quite wrong.”

In the three years of the project so far, Kopp and Sills have identified more than 100 tornadoes that otherwise would have gone undetected.

“We’ve found entire outbreaks of tornadoes completely [using] satellite data that no one knew about beforehand,” says Sills. 

A screenshot of a map showing all the tornadoes reported and/or confirmed in Canada since 2017 through the Northern Tornadoes Project. The events are colour-coded according to intensity, with red and orange indicating the strongest winds, blue and green the weakest. The black pin indicates a reported event still under investigation. Explore the interactive map.

Eyes on the ground

With all the tools and technology at their disposal, Kopp is confident the NTP team will be able to gather just as much data this year as in previous years, even if physical distancing requirements and shifting rules around interprovincial travel mean they can’t visit every site in person. 

On the prairies, where communities are spread out and reliable damage indicators like trees can be in short supply, NTP will be looking to the storm chasing community for extra help. 

Beth Allan, a Calgary-based storm chaser who has contributed reports and on-the-ground images to NTP in the past, says she still plans to head out in pursuit of storms this year, but with a few modifications to her usual routine. 

“I’m going to be more picky about what I chase, and also more self-sufficient — bringing my own food and trying not to have contact with lots of different people,” she says. “There would be nothing worse than discovering that you managed to pick up [COVID] somewhere and then travelled across four provinces, spreading it around.” 

She adds safety is always her primary concern on any chase — her own and that of the people in the path of a storm. 

“It’s about more than just pretty photos,” she says. “The first priority is reporting, and making sure that before anything else happens, the people who need information about what’s happening on the ground get that information.”

Tracking tornadoes

For NTP’s researchers, the investigation process begins days before a tornado has even touched down, with a forecast. NTP meteorologists monitor weather systems and identify areas where severe weather is likely to occur. As thunderstorms begin to fire up in the target area, the researchers will watch radar for signs of rotation within a storm and other indicators that a tornado could be about to form or is already on the ground, such as a hook echo

In populated areas, social media reports can be extremely valuable in the minutes and hours after a severe weather event. Photos of damage are usually the best indicators that something has happened that warrants further investigation, but often amateur weather enthusiasts will capture images of a funnel cloud or wall cloud (a sudden lowering at the base of a thunderstorm that often precedes the formation of a tornado) without realizing what they’re looking at. 

When a tornado is suspected based on radar scans but there are no eyewitnesses, the team will compare daily high-resolution satellite images of the area, which can reveal a damage path through trees or cropland. 

The investigation usually culminates with a visit to the site, where the researchers will examine debris patterns on the ground and perform aerial surveys or send up drones to gather more data. “We can see what types of trees fell, the direction the trees fell, the soil conditions — all of those things that make it easier for us to tell if it was a tornado that occurred or a downburst,” says Sills. It’s this part of the process that may see some changes in COVID-19 times. 

If a tornado is confirmed, the researchers use the type and severity of the damage to estimate the wind speeds within the tornado and give it a rating on the Enhanced Fujita scale, which ranges from EF-0 (105-137 km/h; light damage such as roof shingles peeled off or broken branches on trees) to EF-5 (322 km/h and greater; extreme damage including well-built frame houses completely destroyed and steel-reinforced structures critically deformed). 

Very strong tornadoes are rare in Canada; since 2017 there have been no EF-5 tornadoes, one EF-4 tornado, and a handful of EF-3 tornadoes, including one that struck the rural Ottawa-area community of Dunrobin and tracked into Gatineau, Que. on Sept. 21, 2018. But, Sills says, without a large dataset, it’s hard to know whether strong tornadoes are increasing or decreasing in frequency and where they’re most likely to strike. 

“One of the things we plan to do with this project is establish these baselines of how many of these types of tornadoes are occurring across the country so we get an idea of trends, but it’s going to take time to build that database.”