There isn't so much a shift in severe storm weather activity in Ontario due to global warming, but rather a greater public awareness about the storm activity, an Environment Canada meteorologist told a group attending a presentation on Ontario's Aug. 20, 2009 tornadoes.
The presentation was organized by the Institute for Catastrophic Loss Reduction (ICLR) and hosted in Swiss Re's Toronto office.
Geoff Coulson, warning preparedness meteorologist for Environment Canada, was asked if he saw an increase in storm frequency attributable to global warming. "Not that I've seen," he replied.
"I haven't necessarily seen any trends to say there are more. But I think what we are partially dealing with is more awareness. We've spent the last quarter-century telling people about these storms, what causes them, how to react to them.
"And quite frankly in Ontario we've seen the population explode in the last 25 years. There are people sticking cottages in places that never used to have cottages, and they are finding out those big trees on the lake that were so great for shade aren't so good when they land on your cottage [during a storm]."
The Fujita scale, which helps to determine the strength of a tornado, is based in part on damage done to a structure. With more structures being erected in Ontario's so-called "cottage country" — a broad area often identified as a few hours north of Toronto — more people are reporting damage that they believe could only be done by a tornado.
Coulson said people reporting tornado damage to him are "almost disappointed" to hear the roof blew off their house not because of a tornado event, as they had previously supposed, but rather as a result of a microburst storm, which can in itself cause a lot of damage.
Ontario statistically sees about one F2 tornado touch down each year, but in 2009 the province has thus far been hit by a "bumper crop" of at least five F2 tornadoes, Coulson said. On the Fujita scale, an F2 tornado packs winds of 180-240 km-h.
Coulson said he expects to confirm the 14th tornado from August 20 once inspectors look at damage caused in Buckshot Lake, in the Township of North Frontenac County.
It is now presumed that two F2 tornadoes hit the Vaughn area north of Toronto on Aug. 20. Gregory Kopp, a University of Western Ontario researcher who inspected the damage in Vaughn first-hand, said some evidence suggests one of these F2 tornados might in fact have been a lower-scale F3 tornado (winds of between 250 and 320 km-h).
In Ontario, F4 tornadoes (330-410 km-h) have occurred with a statistical frequency of one every 15 years, said Coulson, adding the last F4 tornado to hit Ontario was in Barrie, Ontario in 1985.
"We are well overdue for an F4 [tornado] in the province," said Coulson.