A mostly dry day can be expected across the Pacific Northwest on Friday although an isolated snow shower cannot be ruled out. Temperatures were mostly in the 20's at NWAC stations early Friday morning with very light winds and weak westerly flow through the mountain gaps. Temperatures should rise above freezing at Snoqualmie Pass level during the middle of the day. After a partly cloudy morning, a weak front approaching the Pacific Northwest will increase cloud cover across the region and should start bringing some light snow to the Olympic Mountains.
The front arrives Friday night with ridgeline SSW winds increasing into the moderate range for the Olympics and the west slopes of the Cascades. Light snow should spread throughout the region by the early morning hours. The pattern changes very little on Saturday as the weakening front stalls over the region with a deeper trough still offshore. The SSW flow favors the volcanoes, particularly Mt. Baker which can expect 6-12" of snow by the end of the day on Saturday. Moderate SSW winds should continue on Saturday.
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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Friday
Mostly clear to start with clouds increasing. Mostly skies with a slight chance of light snow developing in the afternoon.
Friday
Night
Periods of light snow, increasing.
Friday
Partly cloudy with increased sun beaks during the middle of the day, then becoming mostly cloudy by late afternoon.
Friday
Night
Light snow developing during the evening and increasing overnight.
Friday
Partly cloudy with increased sun beaks during the middle of the day, then becoming mostly cloudy by late afternoon.
Friday
Night
Light snow developing during the evening and increasing overnight.
Friday
Partly cloudy in the morning then becoming mostly cloudy in the afternoon with a slight chance of very light snow.
Friday
Night
Light snow developing during the evening hours and increasing overnight.
Friday
Partly cloudy in the morning then becoming mostly cloudy in the afternoon. Light W or variable wind at the Pass.
Friday
Night
Mostly cloudy in the evening with light snow developing during the early morning hours. Light E wind developing at the Pass.
Friday
Partly cloudy in the morning then becoming mostly cloudy in the afternoon. Light W or variable wind at the Pass.
Friday
Night
Mostly cloudy in the evening with light snow developing during the early morning hours. Increasing light E wind at the Pass.
Friday
More sun than clouds.
Friday
Night
Mostly cloudy with a chance of light snow in the early morning hours.
Friday
More sun than clouds through mid-day, then becoming mostly cloudy.
Friday
Night
Mostly cloudy with a chance of light snow in the early morning hours.
Friday
More sun than clouds through mid-day, then becoming mostly cloudy.
Friday
Night
Mostly cloudy in the evening with light snow developing overnight.
Friday
Partly cloudy in the morning, becoming mostly cloudy in the afternoon.
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).