A frontal system stalled over northern Oregon on Sunday continues to deliver a subtropical moisture feed, adding 2"+on Sunday to 3.4" of water equivalent received overnight. This band should be south of the Mt. Rainier area, but may continue to spread some light to moderate moisture into the Mt. St. Helens and Mt. Adams areas through mid-morning. Most of Washington state should see cloudy conditions with light rain and high elevation snow showers and some thin bands of moderate convergence in the Stevens Pass and Mountain Loop areas. Cooler air was slower to arrive in Washington than expected, but temperatures have begun to cool off in the northern half of Washington State.
The lingering frontal band should lift back northward into Washington State as the final strong wave along the subtropical moisture feed approaches Sunday night. Moderate to heavy rain and high elevation snow will spread northward into Washington State overnight along with a sharp warming trend.
The low tracks from WSW to ENE across the Puget Sound and central Washington Cascades leading to a sharp NW to SE gradient in temperatures across the range. Areas such as Mt. Baker, Hurricane Ridge, and Washington Pass may see significant snow accumulations throughout the day on Monday, while areas further SE await the cooling of the cold frontal passage late Monday. Expect strong alpine winds throughout the region. The track of the storm will need to be watched very closely.
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
Cloudy with a chance of a light rain or snow shower.
Sunday
Night
Light rain and snow developing in the evening, becoming moderate overnight.
Sunday
Cloudy with a chance of light rain or snow showers.
Sunday
Night
Light rain and snow showers becoming continuous toward morning.
Sunday
Light rain or snow showers at times, mainly in convergence.
Sunday
Night
Light rain and snow showers becoming with steady rain and snow increasing after midnight.
Sunday
Moderate rain and snow early quickly becoming light or ending.
Sunday
Night
Rain and high elevation snow increasing through the evening and becoming heavy at Paradise and moderate at Crystal and White Pass.
Sunday
Light to occasionally moderate rain or snow showers at times, mainly in convergence. Decreasing light to moderate W winds at pass level.
Sunday
Night
Light rain and snow showers becoming with steady moderate rain and snow developing after midnight. Light W winds shifting E at pass level overnight.
Sunday
Light rain or snow at times, mainly in convergence. Decreasing light to moderate W winds at pass level.
Sunday
Night
Light rain and snow showers becoming with steady moderate rain and snow developing after midnight. Light W winds shifting E at pass level overnight.
Sunday
Very light snow showers near the Cascade Crest. Strong winds in the morning.
Sunday
Night
Increasing light to moderate snow developing overnight.
Sunday
Light snow possible in convergence spillover near the Cascade Crest. Strong winds in the morning.
Sunday
Night
Light rain and snow becoming moderate after midnight.
Sunday
Moderate rain and snow early quickly becoming light or ending.
Sunday
Night
Moderate rain and high elevation snow.
Sunday
Heavy rain and high elevation snow. Mild. Strong ridgeline winds.
Sunday
Night
Very heavy rain and high elevation snow. Mild. Strong to very strong ridgeline winds.
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).