These before-and-after images from NASA's Suomi National Polar-orbiting Partnership (S-NPP) satellite show the power outages in the clear skies over Washington, D.C., and Baltimore that occurred on June 29, 2012. The outages were the result of a derecho, a rare, fast-moving thunderstorm system that packs the power of a tornado.
The derecho combined intense lightning and rain with hurricane-force winds that were upward of 60 miles per hour. It killed 22 people and caused about 4.3 million households to lose power for days.
Derecho is the Spanish word for straight. True to form, the storm raced from west of Chicago straight across Illinois, Indiana, Ohio, West Virginia, Virginia, Maryland and into Washington, D.C. According to the National Weather Service, the gigantic windstorms of a derecho are as powerful as tornados, but the winds don't twist, instead driving in a straight line. To be classified as a derecho, the swath of wind damage must extend more than 240 miles and the storms are powered by hot, humid weather.