The leading factors affecting early-season snow and ski conditions are as follows:
1. High average snowfall. A good rule of thumb is that an area should average at least 300 inches per season to have a better-than-even chance of having advanced natural snow terrain open by Christmas.
2. Consistency of snowfall. A high average does little good if you show up in a year when there was zero in November (i.e., 1995 in California)
3. Intermediate oriented terrain where a three- to four-foot base will get most runs covered. It takes a lot more at expert mountains like Squaw Valley, Snowbird, and Taos.
4. Heavier, wetter snow. Other factors being equal, heavier Pacific type snow will build a higher base than the dry snow of the Rockies.
5. Snowmaking. It's probably the number one factor in the East, but most destination skiers in the West are looking for more than the usually limited fraction of terrain that most Western areas cover with man-made snow.
Click on the related links below (and above right) for more of the Early-Season Ski Vacation Planner.