The weekend starts unseasonably warm on Saturday morning. Nearly all NWAC stations have risen above freezing. Light rain and highest-elevation snow linger along the west slopes and passes on Saturday, with light rain or drizzle focused on the mountain loop to Snoqualmie Pass with a broad area of mid-level convergence. This region is likely to fluctuate throughout the day. Expect significant sunshine east of the Cascade Crest. Snow levels hover around 7000-8000 ft with dry air freezing levels in the 8000-12000 ft range.
After a warm and damp Saturday, the ridge begins to flatten, and temperatures start to drop by the afternoon, slowly at first. A strong cold front moves in from the northwest Saturday night. Moderate to heavy rain and snow develop in the northern Cascades early Sunday morning, with the heaviest precipitation moving through the central Cascades as the morning progresses. Snow levels drop rapidly from NW to SE, starting early in the day in the Mt Baker area. By the afternoon, snow levels lower to around 3500 ft in the central Cascades as post-frontal showers and convergence continue on the west slopes of the Cascades.
Persistent westerly ridgeline winds from Friday night through the weekend peak on Sunday, accelerating through mountain gaps and down the east slopes of the Cascades. These winds are likely to impact lower terrain in mountain gaps as well.
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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Saturday
High clouds over the eastern and northern Olympics with low clouds and very light rain possible further west. Moderate ridgeline winds.
Saturday
Night
Mostly cloudy with increasing light rain and snow overnight. Moderate ridgeline winds.
Saturday
Periods of light rain, highest elevation snow, or drizzle. Light to moderate ridgeline winds.
Saturday
Night
Light rain and snow become moderate to heavy overnight. Moderate ridgeline winds.
Saturday
Periods of light rain, highest elevation snow, or drizzle. Moderate ridgeline winds near the Cascade Crest.
Saturday
Night
Light rain and snow become moderate overnight. Moderate ridgeline winds.
Saturday
Mostly cloudy with drizzle at times for the higher terrain. Moderate ridgeline winds.
Saturday
Night
Increasing light rain and higher elevation snow. Crystal is mostly rainshadowed. Moderate ridgeline winds.
Saturday
Light rain or drizzle at times. Moderate ridgeline and light to moderate W wind at the Pass.
Saturday
Night
Increasing rain and higher elevation snow. Moderate ridgeline and light to moderate W wind at the Pass.
Saturday
Light rain or drizzle at times. Moderate ridgeline and W wind at the Pass.
Saturday
Night
Increasing rain and higher elevation snow. Moderate ridgeline and W wind at the Pass.
Saturday
Partly cloudy with periods of light drizzle near the Cascade Crest. Moderate ridgeline winds.
Saturday
Night
Increasing light rain and higher elevation snow. Moderate ridgeline winds.
Saturday
Partly cloudy with periods of light drizzle near the Cascade Crest. Moderate ridgeline winds.
Saturday
Night
Increasing light rain and higher elevation snow. Moderate ridgeline winds.
Saturday
Partly cloudy with periods of light drizzle near the Cascade Crest. Moderate ridgeline winds.
Saturday
Night
Increasing periods of light rain and higher elevation snow. Moderate ridgeline winds.
Saturday
Mostly cloudy on the west side of the mountain, with mostly sunny skies to the east. Strong to extreme ridgeline winds, particularly on the S and E sides of the mountain.
Saturday
Night
Mostly cloudy on the west side of the mountain, with mostly sunny skies to the east. Strong ridgeline winds, particularly on the S and E sides 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).