A mesocyclone is a vortex 2–10 km in diameter within a supercell, detectable by Doppler radar as a couplet of opposing velocities (rotation). It is the parent structure of most significant tornadoes.
Detection and prediction
Weather radars can detect mesocyclones 20–30 minutes before they produce tornadoes, allowing tornado warnings to be issued. Not every mesocyclone spawns a tornado (only ~25%), but its presence always indicates a severe storm with risks of large hail, destructive winds, and possible tornado. The wall cloud is its visual manifestation.