A mix of cloud cover has moved in overnight, along with cooler temperatures and light to moderate southwest winds across the region. An upper-level front just offshore will move over western Washington on Sunday, producing light to moderate snowfall across most mountain areas.
Precipitation will begin this morning over the Olympics and the northwest Cascades, then gradually spread inland through the afternoon, reaching the southern and eastern zones by mid to late afternoon. Snow levels will fall as showers develop, dropping below the mountain passes by this evening. A Puget Sound Convergence Zone is expected to form near or south of Snoqualmie Pass late this afternoon, bringing periods of localized heavier rain and mountain snow overnight. Ridgeline winds will increase with the front's arrival and remain elevated overnight, with stronger speeds expected for Mt Hood and the mountain passes.
Showers will taper off quickly on Monday as high pressure builds over the region. Clouds will decrease early, leading to mostly clear skies and lighter wind speeds. Low-level clouds may persist east of the Cascade crest. Mountain passes will see a shift to easterly wind, while ridgelines remain WNW. Monday afternoon will see a general warm-up with the sunshine, but remain relatively cool.
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
Light to moderate rain and mountain snow. Light to moderate ridgeline wind.
Sunday
Night
Light mountain snow, tapering off through the night.
Sunday
Light rain and mountain snow, turning moderate mid-morning into the afternoon. Moderate ridgeline wind.
Sunday
Night
Light mountain snow, tapering off through the night. Light to moderate ridgeline wind.
Sunday
Light rain and mountain snow, turning moderate mid-morning into the afternoon. Moderate ridgeline wind.
Sunday
Night
Light mountain snow, tapering off through the night. Light to moderate ridgeline wind.
Sunday
Chance of showers in the morning. Light to moderate rain and mountain snow in the afternoon. Light to moderate ridgeline wind.
Sunday
Night
Light to moderate rain and mountain snow, with the greatest amounts focused near Paradise. Light to moderate ridgeline wind.
Sunday
A chance of showers in the morning. Light to moderate rain and mountain snow in the afternoon. Moderate ridgeline and W wind at Pass level.
Sunday
Night
Light to moderate rain and mountain snow, tapering off late in the night. Moderate ridgeline and W wind at Pass level.
Sunday
A chance of showers in the morning. Light to moderate rain and mountain snow in the afternoon. Moderate ridgeline and W wind at Pass level.
Sunday
Night
Light to moderate rain and mountain snow, tapering off late in the night. Moderate to strong ridgeline and W wind at Pass level.
Sunday
Cloudy in the morning, with light rain and mountain snow in the afternoon.
Sunday
Night
Light rain and mountain snow, tapering off through the night. Light to moderate ridgeline wind.
Sunday
Cloudy in the morning, with light rain and mountain snow in the afternoon. Heaviest precipitation closer to the Crest. Moderate to strong ridgeline wind.
Sunday
Night
Light rain and mountain snow, tapering off through the night. Moderate to strong ridgeline wind.
Sunday
Cloudy in the morning, with light rain and mountain snow in the afternoon. Heaviest precipitation closer to the Crest. Moderate to strong ridgeline wind.
Sunday
Night
Occasional light rain and mountain snow, tapering off through the night. Moderate to strong ridgeline wind.
Sunday
Cloudy in the morning, with light rain and mountain snow in the afternoon. Moderate to strong ridgeline wind.
Sunday
Night
Light rain and mountain snow. Strong ridgeline wind.
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).