Strange Sounds From Front Passenger Wheel

In advance, any advice is greatly, greatly appreciated. Here's the problem.

I have a 2000 Nissan Altima GXE.

* There is a horrific grinding when I brake as though the pads are gone. However, this wasn't progressive, and there is no brake light. It went from fine to bad immediately.

* There is a whirring, scraping that appears to be coming from the right front wheel when I'm driving without applying the brake. I hear it more at low speeds, but that's not to say it isn't there at higher speeds.

* It still drives fine. There's not wobble and I can't tell if the brakes are different or if I'm psychologically finding VERY slight differences in braking because of the loud noise.

* This all started after a couple of days of very heavy rain and moisture. Until that point, it was fine. Is it at all possible water or grit kicked into the wheel would cause both the braking and whirring noises?