Tornadoes typically form during severe thunderstorms known as supercells. These storms are characterized by a rotating updraft, called a mesocyclone, which is a key ingredient in tornado formation. Supercells develop when warm, moist air near the ground rises and interacts with cooler, drier air above, creating instability. This instability, combined with wind shear—changes in wind speed or direction with height—sets the stage for the development of a tornado.