It's going to be a warm start to December with the best snow falling on the West Coast and in the Northeast. The Rockies look pretty mild and dry with only a little snow in Wyoming this weekend. Why the change to warm and dry? Take a look at the graphic. The storm track (jet stream) shifted north, allowing more warm air to flood the Heartland and Rockies, while also keeping the coldest air bottled up in Canada. There are two small dips in the storm track over the West Coast and the Northeast; that's where the best snow will fall.
Northeast: I foresee three shots of snow. The first is Saturday. The better snow is Monday–Tuesday with a Nor'easter type storm. Several inches of snow are possible from Killington, Sunday River, Sugarloaf to Cranmore. Temperatures stay pretty consistent with 20s and 30s throughout the weekend.
California: Big snow continues in the Sierras and Cascades through the start of weekend. Then the best snow shifts north early next week into Oregon and Washington. Three different storms will slide off into the Pacific and slam into the West Coast with copious amounts of moisture. It won't snow every minute of every day, but overall we're talking on/off snow for five days. Resorts around Lake Tahoe like Heavenly and Northstar will do well Friday–Saturday.
Rocky Mountains: A pretty warm and dry stretch is ahead through the weekend. Colorado and Utah look to bear the brunt of the warm, dry weather. Some light snow will fall this weekend in Wyoming at both Jackson Hole and Grand Targhee. Temperatures warm up in Colorado this weekend with highs in the 30s and 40s at ski areas like Aspen, Steamboat, Keystone and Vail. At this point it's going to be awhile before the next big snow hits Colorado.