A tornado emergency is an enhanced version of a standard tornado warning—rather than a new warning type—used by the National Weather Service (NWS) to signal that a large, violent tornado is imminent and expected to cause catastrophic damage and numerous fatalities. Issued within a severe weather statement or the initial warning, it urges people in the storm's path to take immediate shelter in an underground shelter or safe room. The term was first used on May 3, 1999, by David Andra of the NWS office in Norman, Oklahoma, as a massive F5 tornado approached the Oklahoma City metro area, including Moore and Bridge Creek. The 2011 Super Outbreak set the all-time record for the most tornado emergencies issued in a single event. This enhanced warning concept also inspired the development of the flash flood emergency for similarly life-threatening flooding situations.