I was driving in the snow a week ago (I have snow tires) and I noticed a CRAZY noise coming from either the clutch or transmission. I thought I was going to have to park it and call a tow! It was scary. It stopped whenever I came to a stop and when I revved it didn't make the noise. When I started moving again it slowly started making the noise again. Got it home and parked it for the night and the next day it was gone and has been ever since. Weird.
Snow packed in wheels and wheel wells can make some crazy noise, if it disappears after being parked, more than likely that was your issue. It more than likely melted and fell out. I've actually had wheel balance issues with my cars from frozen ice.