push your primary clutch in with your knee and make sure your weights are free moving.
fill the upper a-arm hole with silicone, tape off the brake rotor with gorilla tape and seal the top of the rotor so its not flinging water on your belt causing the slip. theres a hole under the chassis right where the track comes out of the bulkhead that likes to put snow on the clutches too.
may be nothing wrong with them clutches, just getting water in there slipping them, seal them up good and if its still showing these signs then look into clutching issues.
but the rotor flings water right on the primary causing this exact issue if its not sealed.
use silicone all around the plastics where they meet the chassis, also look on top of the side panel right beside your lights snow can get down there and fall on top of you clutches. make sure you seal the whole ducting to the clutches too.
when all thats done, take your primary spring out, and cycle your primary in and out by hand, although i think most are binding up when hot it might show its problem when cold if its bad enough.
-Aksnopro