Tornado Alley is a nickname for a broad section of land in the central U.S. that receives a relatively high number of tornadoes. Several states stretching from Texas to Nebraska to Indiana form this path. It is found roughly from east of the Rockies over to the Ohio Valley area. There is the highest possibility of seeing tornadoes in this area.
The area is susceptible to tornadoes as a result of dry air moving east across the Rocky Mountains meeting moist air moving north from the Gulf of Mexico and cool air moving south from Canada moving over central U.S. Theses tumultuous ingredients form severe thunderstorms which in turn generate tornadoes.
The highest probability for tornadoes to occur in Oklahoma is spring to early summer. Another peak occurs in fall as cold fronts come back in - from October to November.
It is important to note that not every expert agrees on the exact boundaries of Tornado Alley, and that the geographic borders may shift somewhat from year to year based on frequency of tornadic activity. No one should become complacent about the possibility of tornadic activity in their area.