If you are dreaming of a White Christmas, then you have a pretty good chance of having your dreams fulfilled. There will be a break in the action on Wednesday, which will give you your best chance of travelling prior to Christmas. Look for variable amounts of cloudiness with cool temperatures (low 40s in the valleys).
On Thursday a cold winter storm drops out of the northwest, bringing a very good chance of snow accumulation in Reno as early as Thursday morning, but more likely in the afternoon. Snowfall amounts are still a bit uncertain, but several inches in town are a possibility (and a Winter Weather Advisory is posted as a result) and amounts on the order of a foot or more are possible in the mountains (with a corresponding Winter Storm Warning posted up there.)
The storm system should push through by Christmas morning, and will leave behind a very cold airmass, with high temperatures expected to stay below the freezing mark Friday and Saturday, and low temperatures which could drop to single digits (or colder in the outlying valleys) by Saturday morning.