Environment Canada assessing the strength of Westman tornadoes

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Environment Canada has tentatively categorized the tornado that damaged seven homes and destroyed an eighth in Waywayseecappo First Nation on Monday as an EF-2 on the Enhanced Fujita Scale — a tornado classification system that goes up to EF-5.

“The strength is determined by the damage that is done,” Environment Canada meteorologist Terri Lang said. “Certain wind speeds will do certain damage. We’re also looking at the construction — there’s a difference between a tornado coming along and hitting a 100-year-old barn … or a (well-constructed) building with a basement that was ripped off its foundation.”

According to Environment Canada’s website, an EF-2 tornado can have wind speeds between 180 and 220 km/h.

Lang says it’s impossible to determine the category of a tornado just by photographs because not all intensities are created equal.

“The size does not determine the strength,” she said, using the analogy of a figure skater spinning around. “When they want to go faster they pull their arms in. When they want to go slower they take their arms out.”

Three tornadoes are confirmed to have touched down in Westman during Monday’s storm and Environment Canada damage assessors are trying to determine if it was high winds or a fourth tornado that toppled trees and damaged property near Erickson.

Lang says the assessors will be talking to residents in the RM of Clanwilliam — where a swath of trees roughly a half-kilometre wide was flattened by the storm — about damage as well as looking at the pattern of downed trees.

“You can kind of tell if all the trees were thrown in one direction … but if they’re all in a swirl pattern there’s definitely evidence of tornadic winds,” she said, adding that straight-line winds can be just as damaging as tornadoes.

Following Monday’s storm, approximately 700 Manitoba Hydro customers had their power affected in Westman. However, public affairs manager Scott Powell says that number is much lower than previous storms this summer.

“The damage was highly localized and generally on lines serving much smaller groups of customers,” he said. “The really big one two weeks ago, I think we had around 40,000 affected at the height of it.”

Powell says the area east of Erickson was impacted the hardest and a number of Hydro poles and lines had to be replaced. Every customer had their power restored by 6 p.m. on Tuesday.

Several residents in the RM of Clanwilliam expressed concern about the amount of forest that had been damaged during the storm.

Brad Epp, manager of urban forestry health and field services with the province’s Sustainable Development department, says extreme wind storms can cause risks for residents and forests alike.

“Unfortunately, it is part of the natural process … which includes blow-down and insect and disease and forest fires — it’s part of the natural regeneration process,” he said, adding that downed trees are more suseptible to infestation. “There are many insects and disease pathogens that are attracted to open wounds on a tree.”

The rate of forest regeneration, according to Epp, depends on the species of tree and the amount of damage. Hardwood trees might start sprouting new shoots within a year, while softwood and coniferous trees can take decades because their seeds can have a hard time finding good soil with a lot of deadfall on the ground.

A large amount of deadfall in a forest also increases the risk of forest fires by adding dry timber to the forest floor.

Homeowners should also be careful when clearing trees on their property and to call a licensed arborist if the trees are quite large. Epp also advises residents to properly dispose of downed elm trees to avoid spreading Dutch elm disease.

“Don’t transport it around it has to be disposed of at a designated site, like the Brandon landfill, and it has to be chipped or burned,” he said.

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