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.
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.