Perth-area twister reached speeds of 150 km/h and tracked almost 40 km, say tornado researchers

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Researchers with the Northern Tornadoes Project at Western University say the heavy winds that buffeted the Perth area last Wednesday evening have been classified as an EF1 tornado, reaching speeds of 150 km/h.

The researchers viewed a video of a tornado taken on Christie Lake and conducted a drone and ground survey of the area on Saturday and Sunday, said Northern Tornadoes Project executive director David Sills.

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Satellite imagery revealed visible tree damage along a track length of almost 40 km with a maximum path width of 600 metres. Tree and structural damage was reported from the Christie Lake area to the Rideau Ferry area, ending near Jasper, southeast of Smiths Falls. No injuries were reported.

“There was almost a continuous path of damage from Christie Lake to Jasper,” said Sills.

Tornadoes are ranked according to the Enhanced Fujita Scale or EF Scale, which assigns a “rating” based on estimated wind speeds and related damage. The researchers survey tornado-related damage and compare it to a list of damage indicators and degrees of damage to trees and different kinds of buildings, which help estimate the range of wind speeds the tornado produced. 

Tornadoes with a rating of EF0 and EF1 are considered weak. An EF1 tornado produces winds of 135 to 175 km/h. To compare, the tornado that hit Nepean on Sept. 21,  2018, was ranked an EF2. The tornado that hit Dunrobin the same day was classified as an EF3 and was considered the most powerful tornado in eastern Ontario in more than 100 years.

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One of the strongest indicators that it was an EF1 tornado last week was the damage done to a group of old barns in the Christie Lake area.

Often in these cases the winds take the roof off an old structure and the walls collapse, said Sills. The demolished barns were the heaviest damage discovered by the researchers.

As the winds approached, witnesses reported hearing a roaring sound, like a freight train. A strong wind alone will make that sound, said Sills. There can still be a tornado if there is no funnel cloud visible.

The same day heavy winds struck the Perth area, witnesses in Quebec captured video of a possible tornado in the area of Lac Dawson, near Lakefield. There was no damage or injuries reported.

The Northern Tornadoes Project also conducted a ground and drone survey of that area last week, where weak tree damage was discovered. The damage in this case was assessed as EF0 tornado, with an estimated maximum wind speed of 115 km/h. There was not enough information to accurately estimate track length, maximum path width and tornado motion in the Quebec case, said the researchers. Satellite imagery review did not reveal any visible damage. 

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The Northern Tornadoes Project was founded in 2017 with the goal of better detecting tornado occurrence in Canada and improving understanding and prediction of severe and extreme weather.

So far this year, the researchers have confirmed 61 tornadoes across Canada, including the Perth-area twister. There have been 16 confirmed tornadoes in Ontario.

Tornado watches are often issued by weather officials hours before there is any tornado activity, said Sills.

“Any tornado warning is serious. Take shelter,” he said. “Get to the basement away from the windows. It’s debris that causes injuries.”

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