I personally haven't had one in a storm, but the Clip Flashlight has been made for like 25 years (although updated a couple years ago) and still upholds a great reputation so I imagine it would be great. Plus it's a low profile, so it doesn't catch wind. The material sheds water like it's off a duck's back and the bathtub floor is plenty high.
One of the big sales reps for Sierra Designs will actually be hanging out at my place tomorrow, I could get the scoop on extreme weather or most anything else then.
I've got these Clip Flashlights, the Vapor Light 2, Vapor Light XL, and the Zeta 3, all with matching footprints, all in stock so PM me if you're interested.