This morning's run is now in. Today will be snow free for most of western WA...only the Portland suburbs could see a few snow showers and some freezing rain.
The new model runs are somewhat more threatening for the Seattle metro area. The front associated with the upper shortwave (see figure) will come in mid to late afternoon. It is producing more of a trough/low at the surface then earlier runs and now the model suggests light snow over central Puget Sound (see graphic). Not a lot, but enough to whiten the place. Timing--starting roughly 3 PM and continuing for three to six hours. Then whatever snow is left would be in the Puget Sound convergence zone north of the city.
Next threat will be Monday evening with the warm front--could start as snow, with only NW WA getting anything significant (few inches) before it turns to rain as the air warms up.
So today is fine...hit the malls, visit friends, or go to your favorite concert or activity.
Tomorrow is ok till roughly 3PM. Then be careful...this is not going to be a big snowstorm--an inch or two at the most.
Monday is fine. Monday night when you are home there could be some light snow turning to rain Tuesday AM. Commute will be fine Tuesday.
PS: I will be giving a public lecture--"The Secrets of Snow"--at Third Place Books in Lake Forest Park on December 17th at 7 PM, followed by a book signing. In this talk I will describe the unusual circumstances that have to come together for us to get a big snowstorm, details of convergence zone snows, the Fraser River Gap flow, arctic fronts, and more. My favorite topic
