Hi Chris,
I drove up highway 4 last weekend and there was basically no snow in Arnold at 4000ft and several feet at 7000ft. The south end of Mormon Immigrant trail is also at 7000ft so there is likely significant snow on the ground.
USDA shows about 4' of snow at the south end of the road.
www.fs.fed.us
What kind of trail are you looking for? I think most dirt roads in the area are closed to vehicle traffic until after the snow melts. If you do explore Mormon Immigrant trail I recommend checking out the old Iron Mountain Ski area which is nearby.