Tornados form from thunderstorms which contain one or more updrafts (upward moving air which is warm and moist). These updrafts form towering cumulonimbus clouds which race upward and cool to form ice crystals (once they reach the anvil of the thunderstorm). Downdrafts of cold air aloft also occur as the thunderstorm intensifies.

Severe thunderstorms, which is an intense thunderstorm with winds of at least 60 mph, most likely produce tornados.

A thunderstorm capable of producing a tornado requires key ingredients such as: warm moist air, cold air aloft, sometime of wind shear(provides vertical motion) and instability high in the atmosphere, and a trigger.

Tornadic thunderstorms usually occur where cold fronts clash with warm fronts over the Southern Great Plains.

Rising updrafts begin to rotate as wind speed changes with direction and height in the thunderstorm. Along the surface of the earth a horizontal rotating column of air is moved vertically to form a shaft which rotates up through the thunderstorm. This area is where most tornados form.

At some point this rotation becomes so intense that a rotating wall cloud descends from the thunderstorm eventually forming a vortex known as a funnel.

This funnel extends downward to the ground where it is officially deemed a tornado.

Tornados often are spawned by large thunderstorms known as a mesocylclone.

A mesocyclone is a violent thunderstorm in which the entire storm or cell complex is rotating, which gives it a predisposition to produce tornados.

Mesocyclonic thunderstorms are also known as "supercells".