Damage from Alberta tornado ranks it among strongest in Canada's history

The tornado that destroyed several homes in central Alberta on the weekend was one of the strongest recorded in Canada's history, with winds powerful enough to toss a farm combine weighing nearly 10,000 kilograms. 

The Northern Tornadoes Project released Tuesday its preliminary damage analysis for the Mountain View County twister, rating the tornado as an EF-4, which is on the high end of the enhanced Fujita scale, which tops out at EF-5.

"Since we've started tracking tornadoes in the 1900s, only 21 have been rated this severe," said Connell Miller, a survey lead with the team, which works alongside Environment and Climate Change Canada. 

"If you think about it, Canada gets around 100-120 tornadoes per year. That's an incredibly small number of tornadoes being rated this severe."

Not since 1987, when an F-4 ripped through eastern Edmonton and killed 27 people, had such a powerful tornado descended on Alberta. The only other F-4 recorded in the province happened in the Grassy Lake area in 1915.  Environment Canada switched from the Fujita scale to the enhanced Fujita scale in 2013, hence the difference in the EF/F rating. 

In the path of Saturday's twister were several homes, 12 of which were damaged, the report said. Three of the homes were flat-out destroyed while four were left uninhabitable. 

A woman was inside the home when the tornado struck, and she took shelter in the basement. Emergency crews had to clear the wreckage to reach her. 

While her home was blown away, she was left unharmed. 

"It's a miracle nobody was more severely injured or killed in this event," Miller said. 

The surveying team attributed this result to the timely warning issued by Environment Canada. Additionally, the government agency said the tornado warning and its lead time "likely helped to ensure no fatalities occurred." 

Through surveying the wreckage, the researchers determined how strong the tornado was by figuring out what wind speeds would be needed to, say, flatten the walls of a sturdy home or toss heavy farm machinery. 

The single piece of damage from Saturday that stood out to Miller was the lifting of a nearly 10,000-kg combine.

"It's still mind-boggling to me," he said. 

The tornado lifted the combine and tossed it about 50 metres before the machine rolled and came to rest as a "crumpled ball of metal."