A system is for sure moving in from the south. Evening it should hit the Seattle area. There will be some precipitation; big question is how much and what form. It is supposed to be stronger to the south, and weaken somewhat by the time it hits the Seattle area.
Forecasts call for it starting as snow, then changing to sleet, then freezing rain, then plain old rain. Lowland Puget Sound forecast calls for up to 1-3 inches snow accumulation and 0.1 inches of ice. These colliding air masses make it difficult to predict. Immediate Seattle area should warm up faster and may not see much frozen precip.
Freezing rain is the worst for driving, tree damage, etc., but I can't imagine a lot of ice freezing to the field. The ground where we are (45 miles away) is frozen solid- I expect some pretty serious ice before it warms up enough to melt.