Bear's Cage - [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.
The bear's cage usually contains a portion of the updraft base, along with the wall cloud or tornado, and is shrouded on most sides by heavy rain. The only way you can "see in" is from the east or northeast (assuming a typical HP storm). However since the storm is moving in that direction, sometimes at a fast speed, is evolving, and the roads may not agree with such narrow chase strategies, getting near or into the bear's cage can be dicey.
The few times I've been near the bear's cage in a full-blown HP it's been because I was lucky enough to be well-ahead of the storm to get into position.