The EF (Enhanced Fujita) rating for the tornado that took place on Canada Day just north of Carstairs was an EF4.

The severe thunderstorm developed near Sundre and intensified as it approached the Didsbury area around 1:45 p.m. The heaviest damage was reported when the tornado crossed Highway 2A between Didsbury and Carstairs. 

According to the National Weather Service, the Enhanced Fujita Scale or EF Scale, which became operational on February 1, 2007, is used to assign a tornado a 'rating' based on estimated wind speeds and related damage. It is a six-point scale, with zero being the lowest and five being the highest.

Terri Lang, Meteorologist with Environment and Climate Change Canada stated the tornado did a serious amount of damage.

"The path length was about 15.3 kilometres, and the maximum width of the tornado itself was about 620 meters."

The wind speeds of an EF4 tornado can reach up to 310 km/h.

There were 12 residences that were hit by the tornado and according to Lang, three were destroyed, four were left uninhabitable, and five were left damaged.

"Thankfully, it didn't go through a heavily populated area, because those statistics could have been a lot different."

The last EF4 tornado in Alberta was the Edmonton tornado back in 1987, so it is a rare occurrence to have such a strong tornado.

The tornado last year near Bergen was given an EF2 rating.

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