The South Valley Surprise of 2002 was a

Pacific Northwest windstorm Pacific Northwest windstorms, sometimes colloquially known as Big Blows, are extratropical cyclones which form in the Pacific basin, and affect land areas in the Pacific Northwest of the United States and British Columbia, Canada. They form as cy ...

that affected the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

s of

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...

, and

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyom ...

on February 7, 2002.

Overview

The storm underwent

rapid Rapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Rapids are hydrological features between a ''run'' (a smoothly flowing part of a stream) and a ''cascade''. ...

cyclogenesis Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere (a low-pressure area). Cyclogenesis is an umbrella term for at least three different processes, all of which result in the development of some sort of cyc ...

just before travelling inland. The circulation was so small in area that the isobars were compacted tightly, thanks to a strong ridge of high pressure to the south, resulting in sustained winds of 50 mph with gusts above 70 mph. The South Valley Surprise was second only to the

Columbus Day Storm The Columbus Day Storm of 1962 (also known as the Big Blow, and originally, and in Canada as Typhoon Freda) was a Pacific Northwest windstorm that struck the West Coast of Canada and the Pacific Northwest coast of the United States on October 12, ...

in terms of wind speed for the southern

Willamette Valley The Willamette Valley ( ) is a long valley in Oregon, in the Pacific Northwest region of the United States. The Willamette River flows the entire length of the valley and is surrounded by mountains on three sides: the Cascade Range to the east, ...

. The "surprise" was how rapidly the storm organized and matured, and its unanticipated strength. Thus, the public had no idea of the impending storm. The storm was able to tap into the jet stream and aim it towards the surface the phenomenon known as "Jet stream enhancement", which usually occurs in the unstable air found in a cold front in a mid latitude cyclone. The result was extensive damage to structures both directly and indirectly from falling trees and debris.

References

{{DEFAULTSORT:South Valley Surprise Of 2002 2002 meteorology Natural disasters in California Natural disasters in Idaho Natural disasters in Nevada Natural disasters in Oregon Natural disasters in Washington (state) 2002 natural disasters in the United States Pacific Northwest storms 2002 in California 2002 in Idaho 2002 in Nevada 2002 in Oregon 2002 in Washington (state) February 2002 events in the United States

Overview

See also

References