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Canada's Top Ten Weather Stories for 2009

Table of Contents

3. Ontario Tornadoes … Deadly and Destructive 

Map of Canada with affected regions highlighted

Photo of damage from the Ontario tornadoes. Ryan Pimiskern © Environment Canada, 2009

Despite the absence of prolonged heat and humidity this summer, Ontario faced some of the deadliest and most destructive tornadoes in its history. It was a long tornado season, beginning on April 25 and ending on September 28.  Ontario witnessed 29 tornadoes in 2009 which tied the record for the most tornadoes in one year set in 2006.  On average, the province sees 11 tornadoes each year.

During the swift passage of an intense cold front on the warmest day of the spring in April, a spate of fierce thunderstorms broke out across southwestern, southcentral and eastern Ontario. Winds at Toronto Pearson International Airport gusted to 115 km/h – the strongest wind gust reported since January 1978. Power lines and trees came down across the province, knocking out power to 100,000 customers.  Embedded in the thunderstorm cluster were marble-sized hail near Parry Sound, waterspouts in the Ottawa River, straight-line winds and weak tornadoes in Windsor and Ottawa. In Windsor, the roof was ripped off a union hall building with chunks of roofing and shards of glass littering the lawn and front steps. At Ottawa’s Rockcliffe Flying Club, tornadic winds damaged 18 planes. Both tornadoes were F0 in intensity with winds of up to 110 km/h.

On June 25, a powerful storm – including an F2 tornado, the strongest to hit the province in three years ripped through southwestern Ontario. Storm damage was reported from Leamington to Cambridge, with the Tillsonburg-Delhi area being hardest hit. 

Then, after 14 years with no fatalities, Ontario’s tornado season went on to claim four victims. July 9 was the deadliest day with three fatalities in northwestern Ontario resulting from tornadic winds in an area where this weather is relatively rare. Just after 9 p.m. EDT, severe thunderstorms roared eastward into the area producing two separate tornadoes. The second of these struck a fishing and hunting resort on Lake Seul, about 15 km south of Ear Falls. The storm was rated as an F2 tornado with peak wind speeds estimated at between 180 and 240 km/h. The tornado downed several large trees and pulled others by their roots. It shook buildings and speared roofs with 2-ft. by 4-ft. lumber. Powerful winds lifted two cabins and a dock two metres off the ground and tossed them into the nearby lake, spreading debris along the far shoreline. Ironically, the victims were from Oklahoma’s tornado alley, home to some of the deadliest tornadoes in the United States, an area that averages 50 tornadoes a year.

The next fatality hit two weeks before Labour Day, when a highly complex, severe weather outbreak struck the province on August 20. Shortly after noon, a supercell storm developed just south of Lake Huron and tracked northeastward for a remarkable 200 km. The heat and humidity hanging over Ontario increased once the clouds disappeared. A low-level jet stream across the region fed more moisture into the storm; shearing winds helped trigger several violent vortices. At the same time, a squall line developed over Lower Michigan and travelled across Ontario. This system produced straight-line winds from Windsor to northeast of Toronto and destructive tornadoes in Vaughan and Newmarket. While these tornadoes were wreaking havoc just north of Toronto, another series of supercell thunderstorms was spawning tornadoes in portions of Simcoe County and the Muskoka and Parry Sound Districts to the east of Georgian Bay and north towards Lake Nipissing. In total, the day’s weather produced at least 18 tornadoes (a record for the most tornadoes in one day in Canada), including: four F0; ten F1; and four F2. That was the greatest number of F2 tornadoes in Ontario in one day since the Barrie/Central Ontario tornadoes of May 31, 1985. From Windsor to North Bay twisters were hopping, skipping and jumping across the province, randomly inflicting violence at one house but sparing the next. Violent winds snapped trees, lifted roofs, flattened cars, mowed down fences, collapsed farm buildings, and inflicted property losses around $100 million.

The first tornado of the day touched down in the town of Durham in Grey County, killing an 11-year-old boy as he left a nearby conservation area day camp. The same storm continued northeast, producing another tornado near Collingwood. Two hours later tornadoes appeared in the City of Vaughan, north of Toronto.  About 600 homes, mostly in the communities of Maple and Woodbridge, were damaged. Thirty-eight were demolished and declared unsafe. Lampposts were shorn off and pieces of trees, fences and brick were strewn everywhere. Some houses had gaping holes and exposed roof beams, while others were untouched by the storm. In Toronto there were unconfirmed reports of a funnel cloud near the busy intersection of Yonge and Bloor – a rare occurrence. Major flooding occurred along the lakeshore, and at the peak of the storm Hydro One reported that 69,000 customers had lost power.

The season’s final confirmed tornado, an F1, occurred on September 28 in Orono just north of Bowmanville where a barn roof was torn off and the concrete foundation of another barn lifted and ripped up.