Top ten weather stories for 2011: story ten

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10. Wicked Winds from the West

A map of southern Alberta where some of the most powerful winds were experienced in November.

Southern Alberta is one of the windiest regions in Canada. Second only to St. John’s, Lethbridge gets more days with strong winds than any city in Canada, while Calgary – famous for its Chinook blows – is the windiest large city in Canada. During the last week of November, some of the most powerful winds ever recorded in the area ripped across southern Alberta, inflicting many millions of dollars in property damages. It was a classic meteorological set-up, featuring a deep low-pressure system from the northern Pacific Ocean that moved inland across the northern section of British Columbia and Alberta. At the same time, a dominant ridge of high pressure was anchored over the western United States. With the high circulating clockwise and the low moving the other way, the air between was pinched into a jet of fast-moving winds that rushed down the Rocky Mountains and hit the Prairies as a warm, dry and fierce wind. The super-charged Chinook broke records for high temperatures, but even more pronounced were the near hurricane-strength winds. Surface-based wind gusts measured 144 km/h at Claresholm, 131 km/h at Stavely and 117 km/h in Lethbridge. And at a home weather station in Pincher Creek, winds were clocked at 204 km/h. On November 22, wind gusts were so strong near Nanton that eight vehicles were blown off the highway and the roof of a high school gymnasium was peeled away, forcing students and staff to evacuate the premises. The strong winds also contributed to the rapid spread of a fire at a feedlot near Cayley.

© View of Calgary skyline.

Five days later, on November 27, more destructive winds blew into Calgary smashing windows and ripping away at building facades in the downtown. On the 58th floor of one office tower, maximum winds were clocked at 149 km/h. Flying debris became a hazard for both motorists and pedestrians on roads and walkways. Traffic in the downtown core was shut down and officials warned residents to stay indoors and away from windows as glass and pieces of roofing membrane rained down on city streets. Several parked cars were damaged beyond repair – some crushed by falling century-old trees – and the power was knocked out briefly to a number of homes. Outside the city, the RCMP advised large vehicles to stay off highways and slow down. In Lethbridge, a raging grass fire forced at least 125 people from their homes.

It was fortunate the windstorm hit on a Sunday during Grey Cup, with many residents off the streets and glued to their televisions. Miraculously, no one was seriously hurt, although one firefighter hit by falling glass suffered minor injuries. At the height of the storm, Calgary’s 311 and 911 call centres handled four days’ worth of calls in just five hours.

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