I also have a 'ram air' on my Grand Cherokee that I built. the filter has direct exposure to rain and mist through the opening in the grille. I do keep an eye on it in wet weather, but I have yet to have any problems out of it.
Currently in the Teg, I have the stock panel filter installed, until I decide to shell out the $50 to get the drop-in K&N.
Again, I will monitor what gets sucked up in there closely and in worst case, I will add a screen on the inlet.
I'll try to get some pics up tomorrow....

-c