But the latest model runs are suggesting a much colder period next week, one that would be far colder than we have seen in many years.
Since we are looking forward in time for an extended period, we must think probabilistically and thus I will show you mainly ensemble (many forecast) output.
We can start with European Center ensemble forecasts (51 forecasts) for surface temperatures (max and min) over Seattle. The range of their ensembles are shown by the blue bracket, while the ensemble mean (often very skillful) by the green line. Their single high-resolution run by the black line. 50% of the ensemble members are within the green box.
Note that just after the new year, the high temps drop below freezing and then plateau out around 25-28F. But uncertainty gets large as well.
The latest weather.com forecast (which is generally excellent) is going for cold and sunny early next week as the cold, arctic air spreads south. Is there a chance of snow as the cold air moves in? The answer is yes...but the uncertainties are too large to speculate on that now.
I feel sorry for those Northwesteners who have travelled to warmer climes over the holidays....they are going to suffer terribly next week, while the cold-hardened folks who remained will be more comfortable.