A strong high pressure parked over the region continues to bring spring-like (perhaps even summer-like?) weather to the region. Monday will be very similar to Sunday, with sunny skies and very light winds. The only areas of below-freezing temperatures today will be high on the volcanoes (above 11,000 ft) and before inversions mix out around 10 AM, where cooler air has settled into deep valleys. Washington Pass base currently has temperatures in the mid-20s, with the ridgeline 18F warmer.
The high pressure gradually starts to weaken Monday night into Tuesday and shift south as the Pacific Northwest begins the transition back toward a more active weather pattern. But, don't expect any major changes on Tuesday. Temperatures decrease a few degrees and freezing levels lower from 11000 ft to 9000-10000 ft. Gradually increasing light WSW winds will focus the warmest temperatures along the east slopes of the Cascades. Expect inversions to form again in the mountain valleys and passes, mixing out around 10 AM. Wispy high clouds may increase slightly as the day progresses.
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
Warm, sunny, and light winds.
Monday
Night
Unseasonably mild, clear, and light winds.
Monday
Warm, sunny, and light winds.
Monday
Night
Unseasonably mild, clear, and light winds.
Monday
Warm, sunny, and light winds.
Monday
Night
Unseasonably mild, clear, and light winds.
Monday
Warm, sunny, and light winds.
Monday
Night
Unseasonably mild, clear, and light winds.
Monday
Warm and sunny. Light ridgeline and variable winds at the Pass.
Monday
Night
Unseasonably mild and clear. Light ridgeline and W wind at the Pass.
Monday
Warm and sunny. Light ridgeline and variable winds at the Pass.
Monday
Night
Unseasonably mild and clear. Light ridgeline and W wind at the Pass.
Monday
Warm, sunny, and light winds. Low-level inversion mixing out around 10 AM.
Monday
Night
Unseasonably mild and clear. Low-level inversion forming below 5500 ft.
Monday
Warm, sunny, and light winds. Low-level inversion mixing out around 10 AM.
Monday
Night
Unseasonably mild, clear, and light winds. Low-level inversion forming below 5000 ft.
Monday
Warm, sunny, and light winds. Low-level inversion mixing out around 10 AM.
Monday
Night
Unseasonably mild, clear, and light winds. Low-level inversion forming below 5000 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).