Decay of a Tornado
•A tornado may be on the ground for a few minutes to as long
as an hour.
•The typical tornado life cycle concludes as the rear flank
downdraft wraps completely around the tornado circulation.
•In this process, cool, denser air encircles the tornado, eventually
weakening and finally eliminating the tornado’s circulation.
•As a supercell moves, typically
northeastward, the upper part of the updraft that contains the
tornado is tilted downstream by the mid-level winds relative to the lower part of the
tornado.
•As this occurs, the tornado is stretched into
a narrow vortex with a rope-like shape.
•Without an updraft to sustain, the tornado
spins down.