derecho

thumb|right|Timelapse video of a derecho approaching and eventually passing over an airport in South Dakota, United States A derecho (, from , 'straight') is a widespread, long-lived, straight-line wind storm that is associated with a fast-moving complex of severe thunderstorms referred to as a mesoscale convective system.

Derechos cause hurricane-force winds, heavy rains, and flash floods. In many cases, convection-induced winds take on a bow echo (backward "C") form of squall line, often forming beneath an area of diverging upper tropospheric winds, and in a region of both rich low-level moisture and warm-air advection. Derechos move rapidly in the direction of movement of their associated storms, similar to an outflow boundary (gust front), except that the wind remains sustained for a greater period of time (often increasing in strength after onset), and may reach tornado- and hurricane-force winds. A derecho-producing convective system may remain active for many hours and, occasionally, over multiple days.