National Weather Service United States Department of Commerce

May 8th 2009 long lived derecho


Warm and muggy conditions late Thursday night set the stage for severe thunderstorms as rich gulf moisture pooled across southern Kansas. A complex of thunderstorms developed over northwest Kansas Thursday night and intensified once it reached the juicy gulf moisture residing over southern Kansas.  The stronger winds aloft combined with very unstable air over the area to create a rare derecho type thunderstorm complex. 

A derecho (from Spanish: "derecho" meaning "straight") is a widespread and long-lived, violent convectively induced straight-line windstorm that is associated with a fast-moving band of severe thunderstorms in the form of a squall line usually taking the form of a bow echo.  The derecho caused a swath of destructive straight-line winds which began near Harvey county and tracked southeast across the state...see image 1 for the damage path. Also see image 2 for swath of power outages.  Violent winds speeds of 80-100mph knocked down power lines, uprooted large trees, and caused significant structural damage to some buildings...see image 3 for radar image.  The thunderstorms also produced large hail and flooding across the region overnight.

Damage Pictures

Large uprooted tree in El Dorado...picture from Butler County  Emergency Management

Garage with severe damage in Cherryvale

Shed was blown off its foundation in Cherryvale

Large tree uprooted smashes carport in Cherryvale

Car smashed by large uprooted tree in Cherryvale

Refinery 80,000 barrel tank dented from derecho winds near El  Dorado...picture from Butler County Emergency Management