<P> The Midwestern states are very prone to tornado activity, as it is part of "Tornado Alley ." States included in the area that are hit by tornadoes the most are Kansas, Missouri, Nebraska, Iowa, and South Dakota . The Midwestern States are often hit by tornadoes during the late spring and early summer months, especially the months of May and June . This is due to the aforementioned air mass moving northward into the Midwest and combining with another air mass that move southward from Canada . This creates unstable air, creating the potential for storms to strike the most during these months . The frequency begins to decrease in the middle of the summer, as the air mass moves northward into the Great Lakes states . </P> <P> A very notable recent storm that has hit this area was the Northwood, Kansas tornado, in the May 2007 Tornado Outbreak . The tornado apparently strengthened as it neared Northwood, and at 9: 38 pm CDT (0238 UTC), storm chasers reported that it had grown to over ⁄ mile (0.8 km) in diameter . Several satellite tornadoes were observed as the very large wedge approached the town of Greensburg, Kansas . It was an estimated 1.7 miles (2.7 km) in diameter and was later confirmed to have been an EF5 on the Enhanced Fujita Scale (the highest possible rating). Based on the damage produced, winds inside the tornado were estimated to have been in excess of 205 mph (330 km / h). </P> <P> Nebraska is fifth overall for sheer numbers of tornadoes, while Indiana has had 88 violent tornado reports from the 1950--2006 period, more than any state except Oklahoma . Iowa reported 3'900 almost as many as Texas . The deadliest tornado in US history, the Tri-State Tornado, struck Missouri, Illinois, and Indiana in March 1925 . St. Louis, Missouri and neighboring East St. Louis, Illinois have been hit more than once by violent tornadoes, the most notorious of which was the St. Louis Tornado of May 1896 . The New Richmond Tornado of May 1899 and the Flint, Michigan tornado of June 1953 also rank amongst the deadliest tornadoes in US history . The region was badly hit by the Palm Sunday Tornado Outbreak in April 1965 and by the Super Outbreak of April 1974 . According to NCDC figures for the 1950 to 2006 period, Nebraska reported 2,440 tornadoes followed by Iowa (2,185), Illinois (2,086), Missouri (1,922), South Dakota (1,487), Minnesota (1,477), Indiana (1,327), North Dakota (1,216), Wisconsin (1,185), Michigan (981), and Ohio (916). </P> <P> The Southern United States has suffered more tornado fatalities than any other part of the country . Some areas experience repeated damaging tornado events, such as the Tennessee Valley and in northern Alabama . The state of Alabama is tied for the most reported F5 tornadoes . For the period 1950 to 2006, three hundred and fifty eight people were killed by tornadoes in Alabama, ranking the state third nationwide behind Texas (521) and neighboring Mississippi (404). Fourth is Arkansas (336) and fifth is Tennessee with 271 fatalities . </P>

City with the most tornadoes in the united states