The Inverted Shower is a very
dramatic shape distortion of the Cascade. In the trick, one hand is
constantly catching and carrying balls horizontally above the pattern, while
the other hand is catching and returning the balls to the hand on top. While
the Inverted Shower may not seem particularly difficult, the speed and
accuracy required to run the pattern make it one of the most difficult three
ball tricks out there.
There is really only one intermediate step to practice when learning the Inverted Shower. Start by juggling a normal Cascade, and then raise one of the balls up and over your non-dominant hand using your dominant hand. Make an under-the-arm throw with your non-dominant hand, and then drop the ball in your dominant hand down toward your non-dominant hand. Using your dominant hand, you will then claw catch the under-the-arm throw made by your non-dominant hand, and resume juggling the Cascade.
Practice this transition until your are very comfortable with it. After that first claw catch, you simply need to keep carrying balls with your dominant hand and feeding them in with your non-dominant hand. Despite the simplicity of the pattern, the Inverted Shower will take a large amount of practice to master. It would probably be best to begin with just two cycles, and then as your skill level increases you can keep adding in more cycles until you are juggling the Inverted Shower continuously.