Paul Bickford
Northern News Services

Fort Smith (July 11/05) - There is no solid evidence a tornado touched down in Fort Smith last week, although some people think one did.

No one disputes wild weather hit on the afternoon of July 6. A so-called wall cloud - the precursor to a tornado - was seen overhead.

Dave Hehn, right, and his daughter Atikin inspect a tree torn apart by strong winds that ripped through Fort Smith last week.

Powerful winds knocked down trees in a trailer park, with one landing on a truck.

And, between noon and 6 p.m., 30 mm of rain fell on parts of the community, with a 20-minute downpour stopping traffic.

Dave Hehn thinks a small twister knocked down a 70-foot tree onto one of his company's trucks at his trailer park home.

Hehn was not at home when the wind hit, but his 10-year-old daughter Atikin and a friend were in a camper trailer, parked just behind the truck. Atikin says she and her friend were scared when the tree fell. "We heard a big bang. We were very lucky the tree didn't fall a different way."

Still, her father and mother, Shirley, note some trees in the trailer park were twisted like they had been hit by a whirlwind. No other homes or vehicles were hit by falling trees.

Several power lines to homes were knocked down, and electricity was cut off to the whole park for safety reasons while crews repaired the lines.

Hehn says his five-tonne truck is probably a write-off. The tree dented the roof, smashed the windshield and now the driver's door won't open.

Hehn says damage at the trailer park has been the talk of the town. "If I charged $5 for everyone who came to look at the truck, I wouldn't have to put in an insurance claim."

David Purchase saw the wall cloud from a window at the NWT Fire Centre, and even took a picture.

"There was lots of movement in it, but it never started spinning to the point of considering it a tornado," says the assistant duty officer at the centre, which monitors weather during fire season.

"There was no evidence of it touching down," he adds.

Town employee Jay Macdonald also saw the wall cloud while driving to the airport.

"It wasn't spinning like a tornado," Macdonald says, although he notes the front of the cloud was moving.

Purchase notes that for a 20-minute stretch just after 2 p.m., rain from the weather system was also very heavy in the trailer park and airport areas.

"People couldn't drive through it. The windshield wipers couldn't keep up," Purchase said.

Hehn says the rain burst flooded his yard with about a foot of water. At least one neighbour had a flooded basement.

Other areas saw barely more than a drizzle of rain.

Classic set-up

Bev Archibald, the Edmonton-based meteorologist working on contract for the NWT Fire Centre, says July 6 in Fort Smith saw a "classic set-up" for a tornado.

Archibald explained that a very hot, humid and unstable air mass came up from the southeast. It originated in the Gulf of Mexico and spawned tornadoes in Manitoba a few days earlier.

"We had sub-tropical moisture over Fort Smith," she says. A cold front then came from the west.

A wall cloud - a localized, persistent and often abrupt lowering from a thunderstorm - is the initial development of a tornado. If it starts to rotate, it becomes a funnel cloud. If it touches down, it is a tornado.

"When you see that formation, you shouldn't be snapping pictures, you should be going to your basements," Archibald says.

Damage at the trailer park was caused by a microburst of wind, says Archibald, who owns True North Weather Consulting.

If it had been a tornado, she says trailers would have been damaged.

At the airport, not far from the trailer park, a wind gust of about 68 km was recorded at 2:18 p.m.

Archibald says a tornado could have touched down somewhere else in the Fort Smith area, and the evidence may not have been seen.

"We get tornadic activities in the NWT, but nobody sees it," she adds.

Archibald said some tornadoes have been spotted over the years at several locations in the NWT.

The weather system that affected Fort Smith moved on to dump a July daily record of 47.2 mm of rain on Hay River on Thursday.

In the Cameron Hills, rainfall totalled 137 mm over 30 hours.