The science and business of a huge-scale storm

TORNADO MATH IS TOUGH

Throughout Friday, teams of Environment Canada weather investigators were working to figure out how many tornadoes caused the swath of destruction across Ontario. Early estimates put the figure at four, but perfecting the math could take some time as investigators correlate evidence and witness reports. "You have to do a lot of digging before you can make scientific pronouncements in these areas," said Environment Canada weather-preparedness meteorologist Peter Kimball.

HOLDING THE CALCULATOR

Everyone from meteorologists and meteorological technicians to summer interns were dispatched to the four main damage sites across Ontario by Environment Canada. Their assignment? Talk to witnesses, observe damage, take statements and photographic evidence and map the damage fields to trace the path and characteristics of the storm.

DAMAGE FIELDS

While damage was spread across a wide belt of the province, Environment Canada sent teams to four sites suffering the most serious destruction: the Town of Durham, Vaughan, Newmarket and Thornbury. By midday Friday, Vaughan's team concluded that an F2 tornado had touched down. In Durham, meteorologist Geoff Coulson had "no doubt" a tornado of the same scale roared through in a "matter of seconds. The worst of these things can be very, very brief, but it's very, very intense," he said.

SCALE OF DESTRUCTION

Tornadoes are classified on the Fujita Scale (named for the Japanese-American meteorologist Ted Fujita) by the measure of damage they cause. They range from F0 (light, with winds between 64 and 116 kilometres per hour) to the incredible F5, which requires wind measures of 418 to 509 kilometres per hour. F2 tornadoes like the one that struck Vaughan have winds of 181 to 252 kilometres per hour and account for one-quarter of all tornadoes. Only one F5 has been documented in Canada. It struck Elie, Man., on June 22, 2007.

UNLUCKY NO. 11

Ontario, on average, registers about 11 tornadoes per summer, according to Environment Canada. Thursday's storms may have pushed the province just over that mark - as of Wednesday, eight had been clocked so far this season.

FOR THOSE WHO NEED A HUG

"The Insurance Bureau of Canada is there for them," said Peter Warner, acting manager of consumer relations for the Bureau, who spent Friday in Vaughan trying to decode the insurance game for distraught homeowners. "What I'm really trying to do is, I'm trying to say that if the peril, which is wind, caused the damage, it is covered." In other words, "If wind caused a big branch to break and hit someone's home, it is covered," he said.

DOLLARS FOR DAMAGE

Insurance officials are still computing the claims rolling in and plan to survey members in the coming weeks to get an accurate measure. Although an Insurance Bureau spokesman cautioned that the comparison is inexact, it's worth noting that a fierce storm that ripped across the top of the GTA on Aug. 19, 2005, caused more than $400-million worth of damage.

STATES OF EMERGENCY

Both Durham and Vaughan declared states of emergency because of the widespread damage. Hydro One crews spent Thursday night reattaching downed power lines that left some 69,000 homes and businesses in the dark at one point. By morning, power had been restored in many areas serviced by the utility.

MAKING A RUN FOR IT

"The trees started rocking and the top of the house blew off first," Town of Durham resident Jon Eckhardt told The Sun Times in Owen Sound. "I saw the trees starting to fly down and ran for the basement and then when I came up, the barn was gone." Although trapped in the basement of the barn, Mr. Eckhardt's cows were just fine.

CANTELOUPLES OF RAIN

"We couldn't see to the other side of the road because it was a wall of black," Durham resident Philly Markowitz told a local newspaper. "The sky all around us went a yellowy green colour and there were these cantaloupe- size grey balls of rain. It wasn't rain, but it was balls of stuff blowing around. That was at ground level, but everywhere from 10 to 50 feet there was debris. There was a chair, a plastic bag, pink insulation, plastic siding. The debris was flying right above head level and I realized then it was a tornado."

A TRUE CATASTROPHE

West-Grey County Deputy Mayor Dan Sullivan fought back tears during an interview with a local newspaper after the storm, which killed an 11-year-old boy camping in Durham. "In terms of true catastrophes or emergencies this is a tough one. There is a lot of damage, you see the buildings, it's your neighbourhood. ... In some regards you go, wow, look what got missed. You are thankful. You don't like seeing your community like this."

IN ONE CITY, A MIRACLE

Vaughan Mayor Linda Jackson held a late night news conference on Thursday after an F2 tornado tore through her constituency. "It's a miracle that there wasn't a person killed in this incident this evening," she said.