A moisture-laden upper-level shortwave moved through in the early morning hours on Sunday. Showers should taper through the morning areas for the Central Washington Cascades southward with the back edge of the shower activity at the coast as of 7 AM. Further north, a moderate precipitation shield has exited the Olympics and should taper across the north Cascades by around 10 AM, leaving some light sprinkle activity into the mid-day hours. Most areas can expect a mostly cloudy afternoon. 5000 ft high temperatures will be unseasonably mild over the next 24 hours with temperatures in the mid-30s to mid-40s, likely peaking on Monday for areas west of the Cascade Crest.
A warm front brushes NW Washington Sunday evening, with increasing moderate to strong ridgeline winds and rainfall focused on the Olympics and Mt Baker areas. The S winds favor Mt Baker for moderate precipitation, but any precipitation should be mostly light in other areas.
The atmospheric river offshore targets southwestern British Columbia on Monday, leaving most of our region dry. Precipitation could linger into the morning hours for Mt Baker. Freezing levels should rise to 9000-11000 ft across the region and E flow should keep lower level temperatures slightly lower east of the Cascades.
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 rain mostly ends by 7 AM, with a few sprinkles and mostly cloudy skies remaining. Increasing light to moderate ridgeline winds.
Sunday
Night
Cloudy with a chance of light rain in the evening. Increasing moderate to strong ridgeline winds.
Sunday
Moderate rain tapering to sprinkles after 10 AM. Cloudy skies in the afternoon. Moderate ridgeline winds.
Sunday
Night
Cloudy with moderate rain at times. Increasing moderate to strong ridgeline winds.
Sunday
Mostly light showers tapering to sprinkles after 10 AM. Cloudy skies in the afternoon. Light to moderate ridgeline winds.
Sunday
Night
Cloudy with a chance of very light rain.
Sunday
Decreasing mostly light rain showers in the morning. Becoming mostly cloudy in the afternoon. Moderate to locally strong ridgeline wind near the Cascade Crest decreasing into the light to moderate range.
Sunday
Night
Cloudy with a chance of a sprinkle in the evening.
Sunday
Decreasing light rain showers. Mostly cloudy in the afternoon. Mostly light ridgeline and E wind at the Pass.
Sunday
Night
Cloudy with a chance of a sprinkle in the evening. Light ridgeline and E wind at the Pass.
Sunday
Decreasing mostly light rain showers. Mostly cloudy in the afternoon. Decreasing moderate ridgeline and light to moderate E wind at the Pass.
Sunday
Night
Cloudy with a chance of a sprinkle in the evening. Light to moderate ridgeline and light E wind at the Pass.
Sunday
Decreasing light rain showers and freezing rain near Washington Pass elevation. Mostly cloudy in the afternoon.
Sunday
Night
Cloudy with a chance of a sprinkle in the evening.
Sunday
Decreasing light rain showers taper near the Cascade Crest. Then becoming mostly cloudy. Decreasing moderate ridgeline winds.
Sunday
Night
Mostly cloudy. Light to moderate ridgeline winds.
Sunday
Decreasing light rain showers taper near the Cascade Crest. Then becoming mostly cloudy.
Sunday
Night
Mostly cloudy.
Sunday
Decreasing mostly light rain showers during the morning hours. Then becoming mostly cloudy. Decreasing 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).