Tornado climatology
Tornadoes have been recorded on all continents except Antarctica and are most common in the middle latitudes where conditions are often favorable for convective storm development. The United States has the most tornadoes of any country, as well as the strongest and most violent tornadoes. A large portion of these tornadoes form in an area of the central United States popularly known as Tornado Alley. Other areas of the world that have frequent tornadoes include significant portions of Europe, South Africa, Philippines, Bangladesh, parts of Argentina, Uruguay, and southern and southeast Brazil, northern Mexico, New Zealand, and far eastern Asia.
Multiple-vortex tornado
The largest tornado ever documented was a multiple-vortex tornado; it struck El Reno, Oklahoma on May 31, 2013 taking the lives of tornado researcher Tim Samaras, his son Paul, and their TWISTEX colleague, Carl Young. This storm also took the life of local amateur chaser, Richard Henderson. It had a maximum width of and a maximum recorded windspeed of at least , however, due to a lack of property damage, the tornado achieved a rating of EF3 on the Enhanced Fujita scale. Nevertheless, the El Reno tornado is one of the two strongest tornadoes ever recorded in terms of maximum wind speeds, the other being the 1999 Bridge Creek–Moore tornado.