The Pacific Northwest sits at the western edge of a broad, cold upper-level trough. Increasingly cold air continues to slowly settle into the region and Fraser River outflow winds are just starting to pick up speed from western Whatcom County to the northern Olympics, bringing cold air to the lowlands and some light snowfall early in the day for the northern Olympics. Ridgeline winds have become light across most of Washington State with snow showers and snow flurries tapering off during the morning hours from Stevens Pass southward. Areas around Mt. Rainier could see an additional 1-2" of fluffy snow with lesser amounts in most other areas. Skies undergo a clearing trend from north to south across the state as upper-level winds shift northerly. Ridgeline winds remain stronger around Mt. Hood with moderate snow and snow showers continuing through the morning before easing into the light range during the afternoon. We expect 2-5" of snow accumulations for Mt. Hood. Mostly clear skies and light winds will allow temperatures to plummet into the 10s and single digits overnight.
A powerful system dropping down the British Columbia coastline will bring increasing clouds Tuesday morning with light snow developing throughout the region during the afternoon. Easterly winds will increase from the light range into the moderate range during the day as the low approaches. This system will produce significant snow throughout our region Tuesday night through Thursday.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
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Monday
Light upslope snow until mid-morning, then becoming partly cloudy to mostly sunny. Cold.
Monday
Night
Mostly clear. Very cold.
Monday
Mostly clear. Cold.
Monday
Night
Mostly clear. Very cold.
Monday
Mostly cloudy with snow flurries to start the day; clearing from north to south during the afternoon. Cold.
Monday
Night
Mostly clear. Very cold.
Monday
Cloudy with light snow or snow showers in the morning. Partly cloudy in the afternoon. Cold.
Monday
Night
Mostly clear. Very cold.
Monday
Snow flurries or an isolated snow shower to start the day, then decreasing clouds and becoming mostly clear by evening. Light ridgeline and W wind at the Pass. Cold.
Monday
Night
Mostly clear. Very cold. Increasing light ridgeline and E wind at the Pass.
Monday
Snow flurries or an isolated snow shower to start the day, then decreasing clouds and becoming partly cloudy by evening. Light ridgeline and W wind at the Pass. Cold.
Monday
Night
Mostly clear. Very cold. Increasing light ridgeline and E wind at the Pass.
Monday
Partly cloudy to start, then becoming mostly clear. Cold.
Monday
Night
Mostly clear. Very cold.
Monday
Mostly cloudy in the morning with isolated snow showers; clouds decrease during the afternoon. Cold.
Monday
Night
Mostly clear. Very cold.
Monday
Mostly cloudy in the morning with isolated snow showers; clouds decrease during the afternoon. Cold.
Monday
Night
Mostly clear. Very cold.
Monday
Decreasing moderate snow showers become light by the afternoon. Decreasing moderate ridgeline winds.
Monday
Night
A few snow flurries in the early evening, then clearing skies. Very cold.
The NWAC program is administered by the USDA-Forest Service and operates from the National Weather Service Forecast Office in Seattle. NWAC services are made possible by important collaboration and support from a wide variety of federal, state and private cooperators.
The 5000’ temperature forecast does not imply a trend over the 12 hr period and only represents the max and min temperatures within a 12 hr period in the zone. The 6-hr snow level forecast, the forecast discussion, and weather forecast sections may add detail regarding temperature trends.
The snow level forecast represents the general snow level over a 6 hr time period. Freezing levels are forecast when precipitation is not expected.
*Easterly or offshore flow is highlighted with an asterisk when we expect relatively cool east winds in the major Cascade Passes. Easterly flow will often lead to temperature inversions and is a key variable for forecasting precipitation type in the Cascade Passes. Strong easterly flow events can affect terrain on a more regional scale.
Ridgeline winds are the average wind speed and direction over a 6 hr time period.
The wind forecast represents an elevation range instead of a single elevation slice. The elevation range overlaps with the near and above treeline elevation bands in the avalanche forecast and differs per zone.
Wind direction indicates the direction the wind originates or comes from on the 16-point compass rose.
Water Equivalent (WE) is the liquid water equivalent of all precipitation types; rain, snow, ice pellets, etc., forecast to the hundredth of an inch at specific locations. To use WE as a proxy for snowfall amounts, start with a snow to water ratio of 10:1 (10 inches of snow = 1 inch WE). Temperatures at or near freezing will generally have a lower ratio (heavy wet snow) and very cold temperatures can have a much higher ratio (dry fluffy snow).