I have stayed in the park lodging during a week in winter. There were small amounts of snow on the ground at our arrival. A bigger storm occurred at the end of our stay. Chains were required to enter the park, those already in the park could leave without chains. No trailer so not sure of those requirements during a snowfall. I am sure the road could have been closed if necessary. Consider carrying a third propane tank for a stay of more than three days or check if there is an operating refill location that can be reached in a snowfall.