Twisters common on the Prairies

A prairie summer wouldn’t be complete without thunder, lightning, rain and wind.

But sometimes you get more than you bargained for.

Canada has the second most tornadoes in the world, behind the United States, and the Prairies get most of them.

About 43 are recorded in this region each year, typically June to August, compared to 17 in Ontario and Quebec, according to Environment Canada.

The number could be far higher because those that aren’t witnessed aren’t recorded.

Technically, a tornado is a rotating column of air extending from a cumuliform cloud that touches the ground.

They can be hundreds of metres wide and last for hours but can also be small and last for minutes.

And while the very word strikes fear, tornados aren’t the only threats from big wind.

John Paul Cragg, a warning preparedness meteorologist in Saskatoon, said thunderstorms produce other damaging winds such as microbursts, macrobursts, downbursts, squall lines and plow or straight-line winds.

“A lot of people assume that it’s only a tornado that does the kind of destructive damage that people see,” Cragg said.

Straight-line winds from Taber to Bow Island, Alta., in 2008 caused damage along a 30-kilometre path with winds of more than 200 km-h, he said.

Microbursts, or small downbursts from thunderstorms, can cause incredible damage in a small area.

“Everybody thinks that the tornado is the real threat, but it’s winds with thunderstorms in general that’s threatening,” Cragg said.

“These straight-line winds can cover a huge area so they can be more threatening.”

The strength and type of a windstorm is determined by the damage it does, particularly if it happens at night or in an uninhabited area where no one witnessed it.

Cragg said a tornado isn’t confirmed from radar data alone. Environment Canada also relies on spotters to report during or after the event.

Radar can indicate whether a storm is rotating and is capable of producing tornados, but only direct observers can tell if it’s touching the ground.

Defining the type of storm also depends on the damage it does.

“If things have blown down all in the same direction, that could be a good indication of straight-line winds,” Cragg said.

“Or if it looks like there’s a centre and everything is blown down sort of away from that centre, that could be a microburst.

“But tornadic damage looks quite different. You can see the rotation on the ground.”

One side of the tornado will do less damage than the other, depending how fast it is moving and which direction it is turning, he said.

“The motion of the tornado enhances the wind on one side and decreases it on the other, but you have to look at that pattern in the context of the storm and you can determine whether it was straight-line winds or a tornado.”

Pictures of the damage sent to Environment Canada are critical in deciding what happened and how intense it was.

The department has used the Enhanced Fujita scale since April 1, 2013, to measure tornados. It has more accurate wind speeds and damage assessments than the previous Fujita scale.

The top rating on both scales is five and only one documented tornado in history has rated this high: the June 22, 2007, storm at Elie, Man. This was a nearly stationary tornado that fortunately caused no injuries.

The deadliest tornados on record are the Regina Cyclone of June 30, 1912, which was rated F4 and killed 28 people in the city and two in rural areas; the July 31, 1987, F4 tornado at Edmonton, which killed 27; and the Pine Lake, Alta., F3 tornado of July 14, 2000, that killed 12 people at the Green Acres Campground.

On the F-scale, an F4 storm produces wind speeds of 330 to 410 km-h, while an F3 has winds of 250 to 320 km-h.

The newer scale considers F3 to have wind speed of 225 to 265 km-h, F4 to be 270 to 310 km-h and F5 to be anything more than 315 km-h.

Cragg said people always want to know whether a tornado or a plow wind caused the damage they find.

“Having it labelled one way or another helps them discover what it was they experienced,” he said.

Merle Massie, an environmental historian at Biggar, Sask., said tornados carry that extra level of awe.

“I think probably that there’s a certain cachet if it was actually a tornado as opposed to ‘just’ a plow wind,” she said.

“There’s a different level of, not fear factor, but certainly wow factor.”

People are fascinated with tornados. They chase them and make movies about them. Last year a photograph of a Saskatchewan bride and groom, tornado in the background, was shared worldwide on social media.

A tornado hit the Massie family’s farm in west-central Saskatchewan a few years ago, although they weren’t there to see it.

“You could actually track it on the ground in the crop. You could see exactly where it went.”

It moved from one unoccupied farm across three fields to another and struck the Massie yard with such force that it stripped the bark off trees.

“They looked like someone had come along and pressure washed them and took all the bark off all the jack pines,” she said.

She has researched all types of events, including the incredible dust storms produced by plow winds in May 1919 through Sask-atoon, which took the paint off buildings.

Massie said tornados rarely come alone, producing hail or massive rain and flooding.

For farmers, any storm plays into the larger story of their relationship with nature, she added.

“Farming is always a dance with nature,” she said. “You’re betting against the weather every year, and this is almost the largest bet.”

Which wind is which?

Straight-line or “plow” winds

  • cause the most thunderstorm wind damage
  • move horizontally along the ground, away from thunderstorms
  • may cause swirling dust and debris like tornadoes
  • can produce the same roar as tornadoes
  • can be as strong as tornadoes but usually cover larger area
  • winds in excess of 200 km-h have been reported

Tornado winds

  • violently rotating column of air between cloud and the surface
  • can appear as funnels, but vary in appearance, strength and speed
  • most common in afternoon and early evening
  • most in Canada have speeds less than 180 km-h

Hurricane winds

  • average sustained winds of at least 119 km-h
  • often bring threat of local flooding from heavy rainfall
  • categorized based on wind speed using Saffir Simpson Hurricane Wind Scale
  • there are five categories, with category 1 being sustained wind of 119-153 km-h and category 5 having sustained winds greater than 249 km-h
  • hurricanes above category 3 (178-209 km-h) have never been documented in Canada on land

Wind warning

  • issued by Environment Canada when there is steady wind at 60-65 km-h or more or winds gusting to 90 km-h or more

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