The Cottonwood Canyons have very good skiing (meaning much of the off-piste is open and adequately covered) about 50% of the time in mid-December. The steep stuff at Park City group/Snowbasin is probably less than 50/50 until after New Year's.
But the key point is that even in the Cottonwoods it's going to be pretty bad early-to-mid-December about 1/3 of the time. So why would one make an advance commitment to a slow time of year when you can score a good deal at the last minute?
The odds of BCC/LCC being bad by then have gone up a little (obvious because a few big early starts like last year have now been excluded). Same is true for the Sierra and the southern and western areas in Colorado.
The storms are continuing on a northern track. Places like Targhee, Jackson, Fernie, Steamboat, Vail, Winter Park are likely to have more snow than normal when they open. This already true at Lake Louise and Sunshine, though historically snow accumulation is quite gradual at those areas. Summit County in Colorado can be viewed the same way as Louise/Sunshine.
Whistler should be doing well, though not that much is open yet and it's clear that the storms have centered more on Washington/Oregon. I would expect Bachelor to be excellent, but its website is not being very informative yet, so look to see what the base is when they open this coming weekend. Bachelor is pretty much all skiable on a 50-inch base, and I'll be surprised if they don't have it by Dec. 1.
Next week is the right time to make those early December decisions. This coming weekend a lot of destination resorts open in preparation for Thanksgiving, and by how much is open at each area the picture will be more specific and less speculative than I have outlined above.
