The powerful front that moved through Washington state Saturday and Saturday night has stalled over northern Oregon. A low has formed along the front offshore of the California/Oregon border. The low should move NE toward the northern Oregon coastline during the day on Sunday, keeping the front over northern Oregon relatively stationary. This allows moderate snowfall to continue on Mt. Hood with around 5-10" of fresh snow by the end of the day. Limited snowfall will reach the southernmost Washington volcanoes (Adams and St. Helens) during the afternoon as the stalled front begins to lift very slowly northward as a warm front. Most of Washington State should experience mostly fair weather with clearing skies in the north and some high clouds from the central Washington Cascades southward. Temperatures should be seasonable in the 20s and low 30s.
Sunday night, the warm front continues to gradually lift northward due to circulation around a deeper spinning off the coast of northern California. Snowfall should increase across the region with moderate to heavy snow expected for Mt. Hood. Moderate snow may develop in the Mt. Rainier area with light snow reaching as far north as the central Cascades overnight. Easterly low-level flow peaks in the moderate range.
Snowfall increasingly focuses on Washington State on Monday with light to moderate rain and snow across the region. The heaviest accumulations should be on the volcanoes. Temperatures begin to warm as winds turn southerly behind the warm front. Easterly low-level flow should keep the passes cold throughout the day.
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
A low cloud deck below 3000 ft gives way to sunshine.
Sunday
Night
Clear in the evening with high clouds arriving overnight.
Sunday
A low cloud deck below 3000 ft gives way to sunshine.
Sunday
Night
Clear to start, then high clouds increasing.
Sunday
A low cloud deck below 3000 ft gives way to sunshine.
Sunday
Night
High clouds lowering and thickening.
Sunday
Thin, high clouds northern part. Thicker clouds southern part, with light snow developing during the afternoon around Mt. Adams and Mt. St. Helens.
Sunday
Night
Increasing light to moderate snow, heaviest at Paradise and White Pass.
Sunday
Clearing skies. Winds switch E at the Pass early in the morning and increase into the light to moderate range.
Sunday
Night
High clouds lowering and thickening with light snow developing by morning. Moderate E winds decreasing slightly overnight at the Pass.
Sunday
Clearing skies with freezing fog possible early in the day. Some thin, high clouds at times. Winds switch E at the Pass early in the morning and increase into the light to moderate range.
Sunday
Night
High clouds lowering and thickening with light snow developing overnight. Moderate E winds decreasing slightly overnight at the Pass.
Sunday
Clearing skies.
Sunday
Night
Sunday
Clearing low clouds with increasing thin, high clouds.
Sunday
Night
Sunday
High clouds the northern part. Clouds lowering and thickening, then light snow developing during the afternoon in the southern part.
Sunday
Night
Sunday
Moderate snow.
Sunday
Night
Moderate to heavy snow. Strong ridgeline wind gusts.
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).