Tornadoes have struck every U.S. state, including Alaska and
Hawaii. But most tornadoes form in a belt from Nebraska
southward through Kansas and Oklahoma, into central Texas, known
as "Tornado Alley," and in the Southeastern United States. The
four states of FEMA Region VII are situated in the heart of
"Tornado Alley." A tornado is defined as a violently rotating
column of air extending from the base of a thunderstorm to the
ground. Air moves very rapidly upward around a tornado center.
This distinguishes tornadoes from microbursts, which often do
tornado-like damage and can be mistaken for tornadoes. In
contrast to the upward rush of air in a tornado, air blasts
rapidly downward from thunderstorms to create microbursts. A
typical tornado outbreak often features an intense upper-level
disturbance moving across the Plains during spring. This
disturbance provides the strong vertical wind shear that gives
an updraft its twisting motion, turning a normal thunderstorm
into a potentially tornado-spawning supercell