Serpentine belts slipping off after running over a large mud puddle or slushy ice is common with Mopar mini vans from what I've read. The serpentine belt hangs over the edge of the tensioner pulley about 1/16 to 1/8 of an inch and causes excessive wear on the belt, sometimes causing it to shred completely while driving. That has happened to me as well as replacing it with a new belt and having that belt slip off after driving over a large puddle on the side of the road. I have to buy a "Serpentine Enhancement Kit" from Dayco, Continental or Gates in order to fix this issue. The pulleys are grooved instead of smooth, and the belt is double sided groove in order to keep the belt from slipping off the pulley.

I really wish Dodge / Chrysler / Plymouth would have done a recall on this many years ago, but they refuse to accept the manufacturing faults.