Tornado Alley
States such as Missouri, Iowa, Minnesota, Wisconsin, Illinois, Indiana, and western Ohio are sometimes included in Tornado Alley. Research suggests that tornadoes are becoming more frequent in the northern parts of Tornado Alley where it reaches the Canadian prairies.
Michigan
The state averages 30 days of thunderstorm activity per year. These can be severe, especially in the southern part of the state. The state averages 17 tornadoes per year, which are more common in the state's extreme southern section. Portions of the southern border have been almost as vulnerable historically as states further west and in Tornado Alley. For this reason, many communities in the very southern portions of the state have tornado sirens to warn residents of approaching tornadoes. Farther north, in Central Michigan, Northern Michigan, and the Upper Peninsula, tornadoes are rare.