Read the section in the cruising PWS book by Jim and Nancy Lethco on reccomended winter time anchorages. Dont forget that freezing in is a possbility during a cold snap if anchored in a spot that has a freshwater feed. Happened to me once I was, a little worried but the high tide came in and flushed all the ice. The book also has a great section on winter saftey prep that is even more critical given the obvious temp and weather conditions compounded by the fact there is less traffic to assist you if you have trouble.