A strong ridge of high pressure will begin to flatten today as pacific frontal system spreads intermittent high clouds over the area today. Freezing levels and temperatures will generally be mild with a few caveats. Easterly flow will continue to drag low clouds and cold temperatures through the Passes. Low clouds should break up for Stevens and White Pass but may stick around for our lower Pass, Snoqualmie. In a similar vein, the east slopes of the Cascades will start off cooler but milder air will punch through to mid and upper elevations as westerly flow aloft increases.
As the upper level ridge flattens we will see some light precipitation glance the north and central Cascades overnight into early Wednesday morning. There could be some light flurries or even freezing drizzle for areas that do see precipitation. Westerly ridgeline winds will also become moderate later this afternoon through tomorrow and expect even stronger W-NW winds in the alpine.
The upper level ridge will begin to rebuild on Wednesday with clearing skies. Freezing levels will rebound except for slightly cooler conditions sticking around closer to the Canadian border.
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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Tuesday
Partly sunny with periods of high clouds and filtered sunshine. Light to moderate ridgeline winds.
Tuesday
Night
Mostly cloudy. Moderate ridgeline winds.
Tuesday
Partly sunny with periods of high clouds and filtered sunshine. Light to moderate ridgeline winds.
Tuesday
Night
Cloudy with a chance of light snow, rain or freezing drizzle after midnight. Moderate ridgeline winds.
Tuesday
Partly sunny with periods of high clouds and filtered sunshine. Light to moderate ridgeline winds.
Tuesday
Night
Cloudy with a chance of light snow, rain or freezing drizzle after midnight. Moderate ridgeline winds.
Tuesday
Partly sunny with periods of high clouds and filtered sunshine. Light to moderate ridgeline winds.
Tuesday
Night
Partly to mostly cloudy. Moderate ridgeline winds.
Tuesday
Partly sunny with periods of high clouds and filtered sunshine. Light to moderate E winds at Pass level. S winds at ridgeline becoming WNW in the afternoon.
Tuesday
Night
Cloudy with a chance of light snow, rain or freezing drizzle after midnight. Light E winds at Pass level and moderate W winds at ridgeline.
Tuesday
Partly sunny with periods of high clouds and filtered sunshine. Light to moderate E winds at Pass level. S winds at ridgeline becoming WNW in the afternoon.
Tuesday
Night
Cloudy with a chance of light snow, rain or freezing drizzle after midnight. Light E winds at Pass level and moderate W winds at ridgeline.
Tuesday
Partly sunny with periods of high clouds and filtered sunshine. Light to moderate ridgeline winds.
Tuesday
Night
Cloudy with a chance of light snow, rain or freezing drizzle after midnight. Moderate ridgeline winds.
Tuesday
Partly sunny with periods of high clouds and filtered sunshine. Light to moderate ridgeline winds.
Tuesday
Night
Partly to mostly cloudy. Moderate ridgeline winds.
Tuesday
Mostly sunny this morning then partly sunny with periods of high clouds and filtered sunshine this afternoon. Light to moderate ridgeline winds.
Tuesday
Night
Partly to mostly cloudy. Moderate ridgeline winds.
Tuesday
Mostly sunny this morning then partly sunny with periods of high clouds and filtered sunshine this afternoon. Light to moderate ridgeline winds.
Tuesday
Night
Partly to mostly cloudy. Moderate 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).