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. Derechos blow in the direction of movement of their associated storms, similar to a gust front, except that the wind is sustained and generally increases in strength behind the "gust" front. A warm weather phenomenon, derechos occur mostly in summer, especially June and July in the Northern Hemisphere. They can occur at any time of the year and occur as frequently at night as in the daylight hours.

Critera:  The traditional criteria that distinguish a derecho from a severe thunderstorm are sustained winds of 58 mi/h (50 kt or 93 km/h) during the storm (as opposed to gusts), high or rapidly increasing forward speed, and geographic extent (typically 250 nautical miles [280 mi or 460 km] long). In addition, they have a distinctive appearance on radar (bow echo); several unique features, such as the rear inflow notch and bookend vortex, and usually manifest two or more downbursts.

bow echo over Kansas City, Missouri