To get you in a proper (chilly) mood, here is the departure of the average daily temperature from normal over the past two weeks over the western U.S.. Virtually the entire West Coast was 2-4F below normal, with large section of northern CA and southern Oregon 4-7F below normal.
Here in Seattle, the temperatures have been well below normal the past two weeks, with NO days hitting the normal maximum (red line below)
The latest forecasts are emphatic about keeping the Northwest U.S. colder than normal this week, a prediction reflected in the latest NOAA Climate Prediction Center 6-10 day forecasts (see below).
The atmosphere has cooled aloft during the last day and the freezing level has dropped to around 1700 ft, which means a snow level of around 700 ft. But heavier precipitation could bring snow down to a few hundred feet today.
For the next 24 h (ending 4 AM Monday, UW WRF model is predicting some light snow along the coast (which is already happening), moderate snow over the mountains, and light snow in a convergence zone around Everett and over the south Sound. Little near Seattle. Why? Rainshadowing in the lee of the Olympics.
With the jet stream going south of Washington, the heaviest precipitation will be over Oregon and California during the next few days. To illustrate, here is the forecast 72h precipitation total starting 4 AM Sunday (today)--with some areas getting 2-5 inches. Good for water resources.