My 16 year old daughter is going to Park City with a friend and parents for a week in late December. We live in Hawaii and we have traveled to the mainland many times but only during warm weather. She has NEVER seen snow before or experienced any type of winter weather!! How cold does it get that time of year? We are already on line getting snowboard pants and thermal socks and long underwear and of course a very warm coat and boots--------anything else a must?