Not an easy forecast. A cold front will move through tomorrow...bringing rain showers with its passage. Temperatures will cool behind it, and by later tomorrow evening the air mass will be cold enough for lowland snow, particularly where there is significant precipitation . The problem is that Puget Sound will be at least partially rain shadowed (or snow shadowed in this case). There doesn't seem to be much evidence of a convergence zone developing over the central Sound. Another issue is that there really won't be that much precipitation in the cold NW flow.Clearly, there will be far higher chances of snow showers south of Olympia and over NW Washington.
So to summarize...frontal passage tomorrow with some rain. Show showers later tomorrow evening and Thursday morning, not amounting to much over Puget Sound, but perhaps dropping an inch or two in some locations south of Olympia and north of Everett. Not a big deal, really. But we need to watch the model run tomorrow...if the flow was more westerly, allowing a convergence zone to form over the central Sound, it could be more interesting.