On May 4, 2007, the city of Greensburg, Kansas was devastated by an exceptionally strong tornado. With estimated maximum winds exceeding 205 miles per hour and leaving a path of damage up to 1.7 miles wide, the storm would be classified as a rare EF5, the first recorded in the United States since 1999. It eventually calmed, the 95 percent of Greensburg was destroyed, killing eleven people. May 4th began much the same as many other spring days in the Great Plains. Cool, dry air from the north collided with warm, moist air from the Gulf of Mexico, creating the kind of unstable atmosphere so common in "Tornado Alley." An intense low pressure system moved in and stalled over the area during the morning hours, providing all the ingredients forecasters and storm chasing groups expect for severe weather. With an extremely unstable mix of conditions in place, the National Weather Service began issuing watches in anticipation of developing storm activity. By late afternoon and early evening, storms began to erupt across parts of Oklahoma, Texas and Kansas. Although the storms began with moderate, disorganized activity, they quickly developed into explosive, well-organized storms. As the day progressed, the National Weather Service and Storm Prediction Center began releasing more urgent updates to alert the public to the growing danger. Several teams of storm chasers began to approach the southern part of Kansas, where conditions appeared more favorable for tornado development. As evening approached, several storms began to take on the characteristics of a supercell storm. Supercells, which are intense, widely rotating thunderstorms, are the most interesting path that almost caused it to hit the city a second time. The storm system continued, shortly thereafter spawning another massive tornado that damaged the community of Trousdale. In all, the Greensburg supercell alone was responsible for as many as 22 tornadoes, including at least 12 tornadoes confirmed by the National Weather Service. During the three-day outbreak, a total of 123 tornadoes were confirmed across several states. Although Greensburg was almost completely destroyed, the storm helped reinforce the important role storm chasers play in the severe weather monitoring and warning process. By having well-trained and experienced people in the field, meteorologists and weather services are able to better track the exact location and characteristics of tornado events, relaying that information to the public more quickly and accurately than ever before..