Data from NWS Seattle updates here

Discussion — cold weather will grip Western Washington through early next week as modified arctic air moves into the region from Western Canada. Temperatures will be generally below Freezing at night and daytime Highs will reach only the 30s and lower 40s. A dusting of snow is possible Saturday night. A change to Westerly flow aloft middle next week will bring milder temperatures and a chance of rain.
Forecast for 20 foot wind speed (valleys and ridge tops) are 10 minute averages reflecting raws winds.

Western Washington
Fire weather:: zones 658-659 area 5 —
North Cascades National park Mt Rainier National Park mt Baker/Snoqualmie National Forest Gifford Pinchot National Forest 521 AM PST Friday Dec 4 2009

Today —
Sky/Weather: — — — partly sunny. Chance of snow showers. Chance of precip — .20%. Maximum temperature — ..28-38. Minimum humidity — — ..65-80 percent.
    20-foot winds — — . Valleys/lwr slopes — Northwest winds 10 to 15 mph. Ridges/upr slopes — . Breezy. Northwest winds 20 to 25 mph. Snow level — — — .2500 feet. Mixing height — — .400-1100 feet agl. Transport winds — .. Northwest around 15 mph.

Tonight —
Sky/Weather: — — — mostly cloudy. Chance of snow showers in the evening. Chance of precip — .20%. Minimum temperature — ..13-23. Maximum humidity — — ..70-85 percent.
    20-foot winds — — . Valleys/lwr slopes — Northeast winds 10 to 15 mph. Ridges/upr slopes — . North winds 15 to 20 mph. Snow level — — — .500 feet. Mixing height — — .500-900 feet agl. Transport winds — .. Northeast 15 to 20 mph.

Saturday —
Sky/Weather: — — — mostly sunny. Chance of precip — .10% or less. Maximum temperature — ..23-33. Minimum humidity — — ..68-83 percent.
    20-foot winds — — . Valleys/lwr slopes — East winds 5 to 10 mph. Ridges/upr slopes — . East winds 10 to 15 mph. Snow level — — — .500 feet. Mixing height — — .700-1200 feet agl. Transport winds — .. East around 10 mph.

Extended —

Sunday — mostly cloudy. Chance of snow showers. Lows around 14. Highs around 16. Snow level at the surface. East winds around 15 mph.

Monday — mostly cloudy. Lows around 7. Highs around 14. Snow level at the surface. East winds around 10 mph.

Tuesday — partly cloudy. Lows around 12. Highs in the lower 20s. Snow level 500 feet. Northeast winds around 5 mph.

Wednesday through Thursday — mostly cloudy. Lows 21 to 26. Highs 26 to 31. Snow level 500 feet.

8 to 14 day near normal temperatures and above normal precipitation.