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.
Tri-State Tornado
It was a widespread outbreak with severe thunderstorms occurring as far east as Ohio, as far southwest as Louisiana, and as far southeast as Georgia. Strong thunderstorms were reported in a broad area that also included parts of Oklahoma, Michigan, Ontario, Pennsylvania, and West Virginia. Numerous reports of hail and straight-line winds were reported with up to diameter hail recorded (for reference, a softball is in diameter). What began in the early-mid afternoon as discrete supercell thunderstorms eventually consolidated into a potent squall line.