The Pacific Northwest has entered a much quieter weather regime as an amplifying offshore ridge builds influence over the Pacific Northwest. The weather pattern brings dry northerly flow aloft with generally NE ridgeline winds and increasing light E low-level winds through the mountain gaps. This low-level flow is partly driven by a cold pool forming E of the Cascades while subsidence brings warming to areas further west and above the inversion top. Freezing levels will rise from 3000-5000 ft in most areas Monday morning to around 6000-8000 ft west of the Cascade Crest in the afternoon. Further east, expect multiple freezing levels to form in some areas by the afternoon and through Tuesday morning.
Tuesday will be even warmer with freezing levels 8000-10500 ft in most areas. The low-level inversion should weaken during the morning areas except in colder valleys east of the Cascade Crest. Expect thick low clouds along the E slopes of the Cascades below 3000-4000 ft, capped by the inversion. With increased offshore low-level flow, don't expect as much cloud west of the Cascade Crest.
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
Sunny and mild with low cloud possible below 3000 ft.
Monday
Night
Clear and mild with low clouds and inversions below 3000 ft.
Monday
Sunny and mild with low cloud possible below 3000 ft.
Monday
Night
Clear and mild with low clouds and inversions below 3000 ft.
Monday
Sunny and mild with low cloud possible below 3000 ft.
Monday
Night
Clear and mild with low clouds and inversions below 3000 ft.
Monday
Sunny and mild with low cloud possible below 3000 ft.
Monday
Night
Clear and mild with low clouds and inversions below 3000 ft.
Monday
Sunny and mild with low cloud possible below 3000 ft. Light ridgeline and E wind at the Pass.
Monday
Night
Clear and mild with low clouds and inversions below 4000 ft. Light ridgeline and E winds at the Pass.
Monday
Sunny and mild with low cloud possible below 4000 ft. Light to occasionally moderate ridgeline and E wind at the Pass.
Monday
Night
Clear and mild with low clouds and inversions below 3000 ft. Light to occasionally moderate ridgeline and E winds at the Pass.
Monday
Sunny with low clouds and inversions possible below 3000 ft. Light to occasionally moderate ridgeline winds.
Monday
Night
Clear with low clouds and inversions building below 4000 ft.
Monday
Sunny with low clouds and inversions possible below 3000 ft.
Monday
Night
Clear with low clouds and inversions building below 4000 ft.
Monday
Sunny with low clouds and inversions possible below 3000 ft.
Monday
Night
Clear with low clouds and inversions building below 4000 ft.
Monday
Sunny with patchy fog in the morning. Low clouds and inversions possible below 3000 ft. Light to occasionally moderate ridgeline winds.
Monday
Night
Clear with low clouds and inversions building below 4000 ft.
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).