The remainder of the MLK weekend features dry weather under northwest flow aloft as an offshore ridge edges into the region. The major story will be the lingering cold air, which remains fully entrenched at low elevations both east and west of the Cascades. Temperatures in the Puget Sound lowlands are in the teens and low 20s early Sunday with temperatures hovering 0 to -10F for locations below around 5000 ft east of the Cascade Crest and through the mountain gaps. Light WNW winds have managed to warm temperatures above the top of the inversion into the 20s for places like Alpental and the Mission Ridge upper station. Meanwhile, light to moderate E flow undercuts the warmer air through the mountain gaps, creating that sharp inversion which is 20 to 35F for most locations along the spine of the Cascades from Mt Hood to Washington Pass. Expect mostly sunny skies with thin few high clouds at times over the area today with lingering low-level moisture clearing out around Mt Hood by around 10 AM.
Temperatures continue to moderate very slowly on Sunday night and Monday. E winds strengthen slightly through the mountain gaps after easing on Sunday. Thus, expect the unpleasant windchills to continue through the mountain gaps even though most temperatures will be above 0F by Monday. Expect another day of mostly sunny skies on Monday.
Bundle up with extra layers if you head out this weekend, but particularly if you head to the east slopes or passes.
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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Sunday
Mostly sunny with thin, high clouds from mid-morning onwards. Light ridgeline winds. Cold.
Sunday
Night
Mostly clear with thin, high clouds at times. Light ridgeline winds. Cold.
Sunday
Mostly sunny with thin, high clouds from mid-morning onwards. Light ridgeline winds. Cold.
Sunday
Night
Mostly clear with thin, high clouds at times. Light ridgeline winds. Cold.
Sunday
Mostly sunny with thin, high clouds from mid-morning onwards. Light ridgeline winds. Cold.
Sunday
Night
Mostly clear with thin, high clouds at times. Light ridgeline winds. Cold.
Sunday
Mostly sunny with thin, high clouds from mid-morning onwards. Light ridgeline winds. Cold.
Sunday
Night
Mostly clear with thin, high clouds at times. Light ridgeline winds with slightly elevated winds near the Cascade Crest. Cold.
Sunday
Mostly sunny with thin, high clouds from mid-morning onwards. Light ridgeline and E winds at the Pass. Extremely cold below the inversion.
Sunday
Night
Mostly clear with periods of thin, high clouds. Increasing moderate ridgeline and E winds at the Pass. Extremely cold below the 5000 ft inversion.
Sunday
Mostly sunny with thin, high clouds from mid-morning onwards. Decreasing moderate ridgeline and E winds at the Pass. Extremely cold below the inversion.
Sunday
Night
Mostly clear with periods of thin, high clouds. Increasing moderate ridgeline and E winds at the Pass. Extremely cold below the 5000 ft inversion.
Sunday
Mostly sunny with thin, high clouds from mid-morning onwards. Light ridgeline winds. Extremely cold with a very strong inversion.
Sunday
Night
Mostly clear with thin, high clouds. Light ridgeline winds. Extremely cold below the 5000 ft inversion level.
Sunday
Mostly sunny with thin, high clouds from mid-morning onwards. Light ridgeline winds. Extremely cold with a very strong inversion.
Sunday
Night
Mostly clear with thin, high clouds. Light ridgeline winds. Extremely cold below the 5000 ft inversion level.
Sunday
Mostly sunny with thin, high clouds from mid-morning onwards. Light ridgeline winds. Extremely cold with a very strong inversion.
Sunday
Night
Mostly clear with thin, high clouds. Light ridgeline winds. Extremely cold below the 5000 ft inversion level.
Sunday
Mostly sunny with thin, high clouds from mid-morning onwards. Moderate ridgeline winds. Extremely cold under a very strong inversion around 5000 ft.
Sunday
Night
Mostly clear with thin, high clouds. Light to moderate ridgeline winds. Extremely cold below the 5000 ft inversion level.
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).