NEWS

Funnel clouds and tornadoes: Your guide to Manitoba's storms

07/21/2015 06:02 EDT | Updated 07/21/2016 05:59 EDT
This storm season in Manitoba has been a slow one by most counts, says Environment Canada meteorologist Natalie Hasell, since there have been no supercell tornadoes this year when we would typically see a dozen in a given season.

Manitoba has now passed peak tornado season, Hasell told CBC, and despite the multitude of photos flooding social media with sightings of funnel clouds and tornadoes lately, there have been fewer than normal. 

"There are a whole bunch of different things that spin in our atmosphere," Hasell said Tuesday, adding not all rotating columns of air are alike.

"We appreciate the photos, it does help us see what you see. But at the same time I'd rather, instead of you taking photos, I'd really rather you take shelter because you can't tell the difference between [the different types of funnels]," Hasell said.

Here are the meteorological highlights:

Supercell tornadoes

Remember the 1996 movie Twister? Those storms would be the real deal, supercell tornadoes that originate from severe thunderstorms. 

A tornado that struck near Elie, Man. on June 22, 2007 was rated as the strongest tornado recorded to that point in Canadian history and was the only EF-5-rated storm (see below) confirmed in the country.

Wind speeds were estimated at 420 to 510 km/h.

There have been no supercell tornadoes in Manitoba this year, which is what causes Hasell to reason that this has been a slow storm season. 

Landspout tornadoes

These are the types of storms seen in the province this summer, and seen in the video above. 

These tornadoes, although threatening, are much weaker than supercell tornadoes.

"When you're looking at these things, you can't always tell the difference between something that's going to be relatively benign to another that could be devastating," Hasell said. 

These storms typically register as EF-0 on the Enhanced Fujita Scale, seen below. 

There have been six landspout tornadoes confirmed by Environment Canada in Manitoba so far this summer, with three of them in June. This is a pretty typical number to see at this point in the storm season, Hasell told CBC. 

Damage associated with a tornado of this type typically involves broken branches or a few loose shingles. 

Waterspout tornadoes

Regardless of the strength of a tornado, if it occurs over water, it earns the "waterspout" tornado designation, Hasell said. 

She confirmed that Environment Canada had counted one waterspout tornado so far this summer over Lake Winnipeg. 

Funnel clouds

Any type of cloud that takes a cylindrical shape is called a funnel cloud.

"This is the problem with English," Hasell said, adding he wished that at some point clarifying language had been introduced.

A funnel cloud could be a precursor to something like a supercell tornado, or it could be caused by something as simple as a low-pressure system, Hasell said. 

There have been 14 funnel clouds reported to Environment Canada this summer, which is also on par with an average season, she said. 

Tornado classification

On April 1, 2013, Environment Canada adopted the Enhanced Fujita Scale — or EF-Scale — to measure the strength of a tornado (it had been in use in the U.S. since February of 2007). 

It uses speed of winds for classification as well as damage caused; not damage potentially caused, Hasell clarified. So if a tornado touches down in a deserted area, it will almost certainly be rated lower. 

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