The mid-January dry spell continues as an unusually strong high-pressure system remains centered just offshore. The light N winds aloft, rounding the high pressure, will have little impact on surface conditions. The bigger impact remains the subsidence and warming associated with the high. Overnight lows at most NWAC stations remained in the 40s. Inversion conditions exist throughout the region, with temperatures increasing with height up to around 6000 ft. East of the Cascade Crest and through the mountain gaps, a secondary freezing level exists at lower elevations (perhaps rising into middle elevations where the cold pool is deeper in the Methow Valley). This cold-air pool has become shallower but colder over time. Morning temperatures will be in the 20s at many trailhead locations, but expect to climb quickly into spring-like temperatures as you rise into middle elevations. Widespread stratus persists across the Columbia Basin with fingers spreading into deeper valleys throughout the east slopes of the Cascades, reaching as far west as Snoqualmie Pass. Given how cold this air is, it is unlikely to retreat east from the Pass much before noon.
The colder air at low levels continues to drive a moderate pressure gradient and low-level E flow through the mountain gaps. Expect moderate ridgeline winds in localized areas near the Cascade Crest from around Snoqualmie Pass southward. Higher ridgeline areas such as Crystal Mountain aren't receiving these winds, but E winds are cranking through slightly lower elevation areas such as Chinook and White passes early Sunday.
We're not expecting much change in the pattern through Monday morning, other than a very subtle lowering for freezing levels from 10,500-12,000 ft on Sunday to 9,000-11,000 ft on Monday.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
Use dropdown to select your zone
Sunday
Sunny and warm with a temperature inversion below 5000 ft.
Sunday
Night
Clear and mild. Temperature inversions below 5000 ft.
Sunday
Sunny and warm with a temperature inversion below 6000 ft.
Sunday
Night
Clear and mild. Temperature inversions below 6000 ft.
Sunday
Sunny and warm with a temperature inversion below 6000 ft.
Sunday
Night
Clear and mild. Temperature inversions below 6000 ft.
Sunday
Sunny and warm with a temperature inversion below 6000 ft.
Sunday
Night
Clear and mild. Temperature inversions below 6000 ft.
Sunday
Sunny and warm with a temperature inversion below 6000 ft. Mostly light ridgeline and E wind at the Pass.
Sunday
Night
Clear and mild. Temperature inversions below 6000 ft. Low cloud and stratus near and east of the Pass. Light ridgeline and E wind at the Pass.
Sunday
Sunny and warm with a temperature inversion below 6000 ft. Low cloud and stratus near and east of the Pass, retreating eastward by the afternoon. Moderate ridgeline and E wind at the Pass.
Sunday
Night
Clear and mild. Temperature inversions below 6000 ft. Low cloud and stratus near and east of the Pass. Light to moderate ridgeline and E wind at the Pass.
Sunday
Sunny and warm at upper elevations with a temperature inversion below 7000 ft and a secondary freezing level below 5500 ft. Low cloud and stratus in the valleys.
Sunday
Night
Clear and mild. Temperature inversions below 6500 ft. Low cloud and stratus in the valleys east of the mountain.
Sunday
Sun and warm at upper elevations with a temperature inversion below 7000 ft. Low cloud and stratus in the valleys.
Sunday
Night
Clear and mild. Temperature inversions below 6000 ft. Low cloud and stratus in the valleys east of the mountain.
Sunday
Sun and warm at upper elevations with a temperature inversion below 6000 ft. Low cloud and stratus in the valleys.
Sunday
Night
Clear and mild. Temperature inversions below 6000 ft. Low cloud and stratus in the valleys east of the mountain.
Sunday
Sun and warm at upper elevations with a temperature inversion below 6000 ft. Low cloud and stratus in the valleys east of the mountain.
Sunday
Night
Clear and mild. Temperature inversions below 6000 ft. Low cloud and stratus in the valleys east of the mountain.
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).