A deep, cold trough and associated upper low parked off the Washington Coast set the stage for cold temperatures and snow shower activity through the weekend. Winds have shifted SW through W on the back side of an upper-level disturbance that lifted NE through the region overnight. Widespread light to occasionally moderate snow shower activity will focus on the west slopes of the Cascades and Olympics but expect some spillover onto the east slopes. Skies will be mostly cloudy with increased sun breaks in the afternoon, but the daytime heating should create enough instability for some more intense graupel/snow showers.
Snow showers decrease in coverage and become more isolated overnight with partly to mostly cloudy skies. Weak circulation centers should move into southern Washington and northern Oregon on Sunday, re-invigorating shower activity.
Snow levels will fluctuate diurnally through the weekend from 0 to around 1000 ft. Freezing levels will be 1000-1500 ft higher during dry weather.
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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Saturday
Mostly cloudy with scattered light to occasionally moderate snow showers. Heaviest showers on the southwest slopes of the Olympics.
Saturday
Night
Mostly cloudy with scattered light snow showers.
Saturday
Mostly cloudy with scattered light to occasionally moderate snow showers.
Saturday
Night
Mostly cloudy with scattered light snow showers.
Saturday
Mostly cloudy with scattered light to occasionally moderate snow showers.
Saturday
Night
Mostly cloudy with scattered light snow showers.
Saturday
Mostly cloudy with scattered light to occasionally moderate snow showers.
Saturday
Night
Mostly cloudy with scattered light snow showers.
Saturday
Mostly cloudy with scattered light snow showers. Light to moderate ridgeline and light W wind at the Pass.
Saturday
Night
Mostly cloudy with scattered light snow showers. Light ridgeline and W wind at the Pass.
Saturday
Mostly cloudy with scattered light to occasionally moderate snow showers. Light to moderate ridgeline and light W wind at the Pass.
Saturday
Night
Mostly cloudy with scattered light snow showers. Light ridgeline and W wind at the Pass.
Saturday
Mostly cloudy with light snow early, then scattered light snow showers. Moderate ridgeline winds at times.
Saturday
Night
Mostly cloudy with scattered light snow showers.
Saturday
Mostly cloudy with scattered light snow showers. More sun breaks in the afternoon. Moderate ridgeline winds.
Saturday
Night
Mostly to partly cloudy with scattered light snow showers.
Saturday
Mostly cloudy with scattered light snow showers. More sun breaks in the afternoon. Moderate ridgeline winds.
Saturday
Night
Mostly cloudy with scattered light snow showers.
Saturday
Cloudy with light to occasionally moderate snow showers focused more on the western slopes of the mountain. Moderate ridgeline winds.
Saturday
Night
Mostly cloudy with scattered light snow showers. Light to moderate ridgeline winds.
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).