I saw something like this in a tower in Khenarthi's Roost...but I'm pretty sure it was intentional in that case. There was a big rain cloud inside the tower, and a khajiit at the bottom with a mop complaining that he wasn't making any progress.

Gedalya wrote: »

Ok; maybe it is intentional. Leaky roof perhaps?

Possibly. The case I found was definitely intentional. It did happen after a magical hurricaine, and after some kind of storm elemental was dispersed. So it works with the plot of that particular zone. As for yours, I can't really say, because that's the only place I've seen it.