Jul 14, 2009 - 11:40 AM

By Crystal Crimi

OSHAWA -- A weekend storm that ripped up trees and pelted stone-like hail felt like a tornado to some, but was actually a micro burst.

Environment Canada is classifying Saturday's storm as a micro burst with F-zero strength on the Fujita scale after investigating damage in Oshawa on Monday, said Geoff Coulson, warning preparedness meteorologist. The scale measures damage from tornados, down bursts, and micro bursts, with the F-zero rating indicating that wind speeds peaked at 110 kms to 115 kms per hour, he said.

A micro burst is a big gust of wind that acts like a plow and pushes things in one general direction, whereas a tornado tosses things about more chaotically, Mr. Coulson said.

The quick and sudden storm caused a barbecue to end tragically when a tree fell on a 21-year-old woman running for shelter and broke her back.

"It happened so quick, I would say 60 seconds," said Bob Rivard, the barbecue's host and family friends with the victim, Lindsay Vemb.

He's also a Toronto firefighter.

"No lightning, I didn't hear hardly any thunder," Mr. Rivard said.

The barbecue was going great until that point -- the afternoon had been sunny and hot, Mr. Rivard said. Around 7 p.m., people were scattered about outside having cake.

Then the storm hit.

"As it got worse, everyone started running to the house," Mr. Rivard said.

His wife was under a canopy and as he tried to get to her, hail struck him like rocks -- then the canopy was blown away.

Ms. Vemb and several other people were sitting in the gazebo and made a run for the house, he said. The first two people made it OK, but as Ms. Vemb and another girl were running with a man right behind them, the tree fell, landing on both of the women and pinning Ms. Vemb on her back under a tree limb. The other girl received scratches on her face and the guy behind them didn't get hit.

Mr. Rivard and some fellow Toronto firefighters attending the barbecue stayed with Ms. Vemb while they waited for emergency personnel to arrive, making sure she was stable and stayed still. She was taken to Lakeridge Health Oshawa, then transferred to St. Michael's for surgery, he said. Although her back is broken, she has movement in her lower legs, Mr. Rivard added.

In Oshawa's Lakeview Park alone, more than 30 large trees were blown down. The storm's damage will likely keep City staff busy for the next several weeks, said Bill Slute, Oshawa's manager of park services.

The International Festival took place in the park this past weekend and no injuries were reported during the storm, Mr. Slute said. The area's trail system is temporarily closed because of trees blocking its path and broken limbs hanging in the canopy of leaves.

In Whitby, the storm hit a strip between Rossland Road and Powell Road, stretching between Brock Street and Garrard Road, said Terry Carson, the Town's superintendent of operational services. It took out about 46 big trees and has left bits and pieces of others throughout.

"Mansfield Crescent was the worst hit ,I think, about five or six big trees down," Mr. Carson said.

Residents can call their municipality to report trees down on public property.

If people have or find ash trees down, they should not transport the wood because of the emerald ash borer beetle that could be present on them, Mr. Slute said. If they're not sure if that's the kind of tree it is, they can check Oshawa's website. www.oshawa.ca, as well as the Canadian Food Inspection Agency.