What are the reasons for the formation of tornadoes in North America?

A tornado is a whirlwind emerging from thunderclouds, pulling in objects of different sizes, on average, its bottom reaches a diameter of 400 meters, and a height of 1.5 km. Causes catastrophic damage: pulls trees, destroys entire buildings, overturns and lifts cars. Most often, tornadoes visit North America, about 700 times a year. This is due to the location of the continent. When the westerly winds over the Rocky Mountains pass into the flat part, they intersect there with the warm winds from the Gulf of Mexico. When they collide, a tornado arises.