[Slang], a region of storm-scale rotation, in a thunderstorm, which is wrapped in heavy precipitation. This area often coincides with a radar hook echo and/or mesocyclone, especially one associated with an HP storm. The term reflects the danger involved in observing such an area visually, which must be done at close range in low visibility.
BEAR'S CAGE
Meaning of BEAR'S CAGE in English
Weather and meteorology English vocabulary. Английский словарь погоды и метеорологии . 2012