They talk about places in Yellowstone getting heavy snow and good amounts of it every year in winter. it is sometimes unknown to people as they only assume Yellowstone is a location to visit in the summer.

According to americansouthwest.net, over half of Yellowstone's annual precipitation falls as snow. 150 inches in most areas but up to 400 inches on the high mountains! The 150 inch average was data taken in the 7,000 elevation range, some areas of Yellowstone over 9000 feet receive a lot of snow. With the fact that most of all the park is above 7,000 elevation it does get colder as well.

If you think 400 inches is a lot ( and it is ) just keep in mind it is not anywhere near as snowy as other areas. 1998-99 1,140 inches was recorded at Mount Baker Ski Area. That is a lot of snow...