Derecho

Combining all of the above, the Arkansas Valley, Ouachita Mountains, Interior Plateau, and Southwest Appalachian ecoregions have the greatest risk of wind damage from tornadoes and derechos, whereas weakening hurricanes are an important disturbance, especially in the Piedmont ecoregion.

Derechos have winds as powerful as those of some hurricanes and tornadoes. "Derecho" comes from the Spanish word meaning "straight."

A derecho can be as destructive as a weak to moderate tornado, but the damage is mainly the result of straight-line rather than rotating winds. However, tornadoes can also form along the bow of a derecho. Derechos can sometimes be recognized as a bank of ominous-looking "shelf" clouds that appear darker than normal clouds.