Shelf clouds were seen along the line of storms. Major US cities, such as Kansas City and St. Louis, got a taste of strong winds and heavy rain from these apocalyptic-looking clouds.
The term "derecho" is Spanish for the word straight. It was first defined by physicist Dr. Gustavus Hinrichs in his paper in the American Meteorological Journal in 1888.
The National Weather Service defines derechos as "widespread, long-lived wind storms associated with a band of rapidly moving showers or thunderstorms."
Hurricane force winds and flash flooding are typical of derechos.
More than 14 states felt the impact of the storms.
Three people were killed Friday as a result of winds toppling trees onto vehicles and a boat, according to authorities.