Utah's Worst Windstorm in a Decade
On December 1, 2011, Northern Utah (where I grew up and my parents still live) experienced hurricane-force winds, with gusts of 90 to 100 miles per hour. The police declared school closed in Davis County, due to power outages and concerns that school buses would tip over in the gale-force winds. In my parents' neighborhood, nearly all mature trees were damaged or tipped over, including dozens of huge pine trees in the neighborhood park.
According to Christopher Smart at the Salt Lake Tribune (http://www.sltrib.com/sltrib/news/53029513-78/winds-mph-pressure-utah.html.csp):
The east-to-west wind storm was caused by a cold air mass coupled with a high-pressure system in Wyoming and low pressure in southern California and Nevada, said Larry Dunn, meteorologist in charge at the National Weather Service’s Salt Lake City office. The unusual pressure imbalance set up cold winds that were channeled from the high pressure to the low.
He compared it to water going over a dam. In this case, the Wasatch Mountains served as the dam.
"The cold air is like water going over the top of a dam in a big sheet and it comes crashing in a big wave at the bottom," he said. "It’s at the bottom of the dam where the winds are most pronounced. In this case, that’s the Wasatch Front."
The winds were fiercest in places where the mountain range is relatively narrow, Dunn said, such as Centerville, where gusts hit 102 mph. By contrast, in places like Sandy, where the mountains are higher and wider, the winds are less strong during such down-slope wind events.
(see above link for full article)
For photos of damage (including trees uprooted, semis flipped over, roofs pulled off, etc) see this gallery from The Standard Examiner: http://www.standard.net/slideshows/2011/12/01/high-winds-cause-damage-all-over-northern-utah