It's not a dish per se, it's just something similar to it in form, in this case it's just what happens when the tip of waterspout, that's directed vertically, crashes down due to gravity. The water at the tip can't fall right down, because there is always a new supply of water coming from down there, so it pushes down on this "new" water and extends in a disk or dish form, then it can finally fall down of the edges of this "accretion disk", hence "как отламывались её края, как падали струйками".

I hope this helps