Tuesday, September 7, 2010

Huge Windstorm Spawns New Classification: 'Super Derecho'

The radar image on the left, taken at 11:56 a.m. on May 8, 2009, shows the super derecho's bow-shaped structure, with a tropical-storm-like eye in the center. A model forecast (right) accurately predicts this rare structure. Credit: NOAA/NWS/Morris Weisman.

From Live Science:

A windstorm that swept across Kansas, Missouri and Illinois in May 2009 was so fierce that it has earned a brand-new name: super derecho.

A derecho (from the Spanish adverb for "straight") is a long-lived windstorm that forms in a straight line — unlike the swirling winds of a tornado — and is associated with what's known as a bow echo, a line of severe thunderstorms. The term "derecho" was first used over a century ago to describe a storm in Iowa. Across the United States there are generally one to three derecho events each year.

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