An upper low off the California coast ejects northward through Tuesday, bringing mostly light precipitation. Much of that precipitation falls as rain for ski area elevations to the west of the Cascade Crest. Inversions remain in place across the E slopes of the Cascades and through the mountain gaps, so expect a wintry mix in these areas by the time precipitation arrives.
Cloudy skies cover the Pacific Northwest on Monday morning. A weak disturbance passed east of the Cascades early this morning, bringing very light rain to Wenatchee, but mountain locations have remained dry thus far. A second wave of moisture moves currently over southern Oregon moves northward into the region by the afternoon and through the northern portions of Washington state during the evening hours. Another band of light to moderate precipitation moves northward in the early morning hours on Tuesday through the end of the day.
The devil is in the details for the east slopes of the Cascades and mountain gaps. For places like Snoqualmie Pass and Stevens Passes, precipitation likely starts as freezing rain or sleet, may mix with snow through late morning on Tuesday, and then changes back to rain. Snow accumulations are more likely for Stevens pass with 1-4" possible. Washington Pass should remain mostly snow. The system ends warm as E winds ease somewhat and SSW flow continues.
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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Monday
Cloudy with light rain and high-elevation snow showers from mid-morning onwards. Light ridgeline winds. Mild.
Monday
Night
Periods of light rain and highest elevation snow at Hurricane Ridge. Precipitation may be moderate over the southern Olympics.
Monday
Cloudy with light rain and high-elevation snow showers late in the day. Light ridgeline winds. Mild.
Monday
Night
Periods of light rain and snow. Light to occasionally moderate ridgeline winds.
Monday
Cloudy with light rain and high-elevation snow showers late in the day. Light ridgeline winds. Mild.
Monday
Night
Periods of decreasing light rain and snow. Light ridgeline winds.
Monday
Cloudy with light rain and high-elevation snow showers in the afternoon. A wintry mix is possible near the mountain gaps with strong inversions likely in these areas. Light ridgeline winds.
Monday
Night
Periods of light rain and snow with mixed precipitation possible closer to the Cascade Crest. Light ridgeline winds.
Monday
Cloudy in the morning with a chance of mixed precipitation or light snow late in the day. Light ridgeline and E wind at the Pass.
Monday
Night
Increasing periods of snow with mixed precipitation also possible. Mostly light ridgeline and E wind at the Pass.
Monday
Cloudy in the morning with a chance of mixed precipitation or rain late in the day. Moderate ridgeline and E wind at the Pass.
Monday
Night
Increasing periods of snow or mixed precipitation. Moderate ridgeline and E wind at the Pass.
Monday
Cloudy with light ridgeline winds. A weakened inversion at the Pass.
Monday
Night
Periods of light snow. Light ridgeline winds.
Monday
Cloudy with periods of light mixed precipitation or snow more likely in the afternoon. Light to occasionally moderate ridgeline winds. Inversions in many areas.
Monday
Night
Periods of light mixed snow, sleet, and freezing rain. Light ridgeline winds.
Monday
Cloudy with periods of light mixed precipitation or snow more likely in the afternoon. Light ridgeline winds. Inversions in many areas.
Monday
Night
Increasing periods of light mixed snow, sleet, and freezing rain. Minimal snow accumulations. Light ridgeline winds.
Monday
Cloudy with light rain and snow. Mild. Increasing light to moderate ridgeline winds.
Monday
Night
Increasing periods of light rain and snow. Increasing 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).