Nothing about it on the AToC site.
I'd guess that even if it snowed overnight, the road would be passable by the time they got there sunday. A lot of people, including my group secretary, commute through there to Pasadena, and I don't recall any recent times when the road's been impassable.
It could be a much more unpleasant ride than stage 4 though-- I rode GMR today and got caught in light cold rain up at about 4000' and it was no fun (we were a bit underdressed). I was certainly feeling for the racers plight tomorrow as we rode down (very chilly!).