MAMMOTH HOT SPRINGS, Wyo. - For those looking to make the most out of the winter season by exploring the colder side of Yellowstone National Park, it's almost time.Park officials announced this week that Monday, Dec. 15 marks th e first day of the winter visiting season.Starting then, you can travel most of the park's roads from the west, south, east and north entrances by approved commercially-guided snowmobiles and snowcoaches.Visitors will also be able to travel into the park with the non-commercially guided snowmobile access program.Park officials say the amount of snow in the park varies, so the type of transportation used on roads depends on conditions.Park staff will keep a close eye with all operators throughout the winter months as conditions change. ...read more read less