A week-long heat wave and an upper level disturbance over Chicago combined to spawn an historic storm featuring a rare and destructive phenomenon known as a derecho. A derecho is a widespread, long-lived wind storm that is associated with a band of rapidly moving showers or thunderstorms. Although a derecho can produce destruction similar to that of tornadoes, the damage typically is directed in one direction along a relatively straight swath. As a result, the term "straight-line wind damage" sometimes is used to describe derecho damage. By definition, if the wind damage swath extends more than 240 miles (about 400 kilometers) and includes wind gusts of at least 58 mph (93 km/h) or greater along most of its length, then the event may be classified as a derecho. This movie shows imagery from the GOES East satellite starting at 0015Z on June 29, 2012 and ending 2345Z on June 30, 2012.