From the southwest came the turbulent and changing winds of an upper-level atmospheric disturbance. The dry line and the disturbance collided, creating strongly rotating thunderstorms that, in turn, triggered the tornadoes. Kan. A tornado's strength depends on the instability of the atmosphere that fuels it.
Tornadoes usually form where cool dry air collides with warm moist air, creating thunderstorms.
At different heights within a storm, winds blow in different directions and at different speeds. Eventually, the spinning intensifies enough to form a funnel cloud, which can drop to the ground as a tornado. Monday, the winds and temperatures over central Oklahoma changed dramatically at different heights in the atmosphere, Eilts said. At the very top of the storm flowed a jet of air, stronger than normal, that helped the vortex spin up even faster. And at the top of the storm there was no temperature inversion, a warmer layer that can stop air from moving vertically and fueling the rotation.