Radar Evidence

• Mesocyclone
  The large rotating updraft that occurs within a supercell is called a mesocyclone when identified by Doppler radar. The WSR-88D Mesocyclone Detection Algorithm analyzes radar data and looks for a rotation pattern meeting specific criteria for size, strength, vertical depth, and duration. The mesocyclone is usually 2-6 miles in diameter, and is much larger than the tornado that may develop within it.
  
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• Tornadic Vortex Signature
  The Tornadic Vortex Signature, or TVS, is a Doppler radar velocity pattern that indicates a region of intense, concentrated rotation. The TVS appears on radar several kilometers above the ground at least ten minutes before a tornado touches ground. It has smaller, tighter rotation than a mesocyclone. While the existence of a TVS does not guarantee a tornado, it does strongly increase the probability of a tornado occurring.
  
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• Hook Echo
  Hook echo is a term used to describe a pattern in radar reflectivity images that looks like a hook extending from the radar echo, usually in the right-rear part of the storm (relative to the motion of the storm). A hook is often associated with a mesocyclone and indicates favorable conditions for tornado formation The hook is caused by the rear flank downdraft and is the result of precipitation wrapping around the back side of the updraft.
  
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