The deadly tornado that struck Joplin, Missouri, on May 22, 2011 had its rating changed from EF4 to EF5 (the highest rating for a tornado), according to the survey by National Weather Service.
An earlier survey has reported the tornado to have EF4 rating. But after examining the damage closely, the National Weather Service has upgraded the rating to EF5, which is the highest rating of the six categories (EF0 to EF5) for a tornado.
The Joplin tornado, with estimated wind speed of over 200 mph, has killed 124 people and injured more than 750, according to an authority reported by CNN.
In addition to personal casualties, around 8,000 structures are estimated to have been damaged or destroyed.