Definitions for "HOOK ECHO"
The shape of a severe thunderstorm echo on a radar screen which denotes the presence of a tornado. The echo is in the form of a hook, or appendage extending off of the main storm echo. Most often seen in the radar imagery of Midwest or great plains storms - very rarely seen in Arizona radar imagery.
A radar pattern sometimes observed in the southwest (right, rear) quadrant of a tornadic thunderstorm. The rain echo forms the hook pattern as air rotates around the strong updraft. The updraft is the hollow portion of the hook (looks like a backwards "J" or a 6) and is where the tornado would most likely be found (if the storm were to produce one). This signature is in the radar reflectivity field; Doppler radar's velocity information can help confirm the presence of a tornado, especially when a hook echo exists in the reflectivity field.
A radar reflectivity pattern characterized by a hook-shaped extension of a thunderstorm echo, usually in the right-rear part of the storm (relative to its direction of motion). A hook often is associated with a mesocyclone, and indicates favorable conditions for tornado development.