DefinitionA derecho (pronounced "deh-REY-cho") is a widespread, long lived windstorm that is associated with a band of rapidly moving showers or thunderstorms. Derecho is a Spanish word for "direct" or "straight ahead" while tornado is thought to come form the Spanish word "tornar" which means "to turn".
Derechos have the ability to cause very long and wide areas of wind damage.
TypesDerechos are sometimes referred to as bow-echoes. However, a derecho may be more than one bow-echo. Because of the variability, there are actually different types of derechos.
This is a situation when multiple bow echoes are embedded in a long squall line that is often hundreds of miles long. This type is caused by a strong, migratory low pressure system.
These derechos are shorter (40 to 250 miles in length) that can actually look like one large bow echo. Although these can last for hundreds of miles, the width is often very narrow. These are often associated with an area of low pressure near the surface.
This derecho has characteristics of both the previous two types.
How And When They HappenDerechos typically happen in the late spring and summer. They occur mostly in the Corn Belt and the southern Plains. While derechos are more likely to occur from May through August, they can happen year round. They typically occur in warm, moist air, like most thunderstorms.