Tornadoes in the United States
The Midwestern states are very prone to tornado activity, as they are part of "Tornado Alley." States included in the area that are hit by tornadoes the most are Oklahoma, 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.
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.