This image from GOES East, taken at 2310Z on May 31, 2013, five minutes after the NOAA National Weather Service Storm Prediction Center received a report of a tornado on the ground, shows the massive system that spawned a long track tornado, assigned a rating of EF-5 on June 4, 2013, that caused extensive damage in areas around El Reno and Union City, Oklahoma. Three seasoned tornado researchers were among the deaths attributed to an extended tornado outbreak from May 26 through May 31, 2013.