What is a Derecho?

So far this year, central Alabama has experienced an abundance of severe weather events. Some of these severe weather outbreaks involve a straight line of thunderstorms called a "squall line."

If a squall line travels many miles and contains destructive "straight-line" winds, it may be called a Derecho.

A Derecho (pronounced similar to "deh-RAY-cho" in English) is a widespread and long lived windstorm that is associated with a band of rapidly moving showers or thunderstorms. Derecho is a Spanish word which can be defined as "direct" or "straight ahead" while tornado is thought by some to have been derived from the Spanish word "tornar" which means "to turn".

Derechos are associated with a band of thunderstorms that are often "curved" in shape. These bowed out storms are called "bow echoes". The bow echo is caused by the precipitation in these strong thunderstorms being forced in a forward direction by very fast moving winds. As these winds plummet toward the ground they hit the ground and speed forward as a microburst containing winds that can exceed 100 mph! A derecho can be associated with a single bow echo or multiple bow echoes.

So, the next time the CBS 42 Weather Team reports a long-lived line of thunderstorms moving into central Alabama, you will know that a derecho may be heading your way with dangerously destructive winds.