The PNW has entered a prolonged dry period, protected from the storm track by an offshore ridge of high pressure.
Sunday starts chilly. Many mountain locations start the day in the 10s and low 20s with light N and NW winds permitting cold air pooling and weak inversions in some valley locations. Temperatures remain cool for mid-April with 5000 ft high temperatures in the 30s across the region. The morning should feature full sunshine. Popcorn cumulus clouds are likely to develop during the afternoon with more clouds likely in the North Cascades than in other locations.
Sunday night, temperatures should be cool, but not as cold as Sunday night. Temperatures drop into the 20s in most locations under light winds and mostly clear skies.
Temperatures continue to moderate to near seasonal norms by Monday. A weak upper-level trough moving southward from interior British Columbia generally lacks moisture. It may bring partly cloudy skies to the region and a very slight chance of light rain or snow showers to the east slopes 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
Mostly clear in the morning with scattered clouds in the afternoon.
Sunday
Night
Mostly clear skies with thin, high clouds possible after midnight.
Sunday
Mostly clear in the morning, becoming partly cloudy in the afternoon.
Sunday
Night
Mostly clear skies.
Sunday
Mostly clear in the morning with scattered clouds in the afternoon.
Sunday
Night
Mostly clear skies.
Sunday
Mostly clear in the morning with scattered clouds in the afternoon. Light W wind at the Pass.
Sunday
Night
Mostly clear skies.
Sunday
Mostly clear in the morning with scattered clouds in the afternoon. Light W wind at the Pass.
Sunday
Night
Mostly clear skies. Light W wind switching E at the Pass.
Sunday
Mostly clear in the morning with scattered clouds in the afternoon.
Sunday
Night
Mostly clear skies. Light W wind switching E at the Pass.
Sunday
Mostly clear in the morning, becoming partly cloudy in the afternoon.
Sunday
Night
Mostly clear skies.
Sunday
Mostly clear in the morning with scattered clouds in the afternoon.
Sunday
Night
Mostly clear skies.
Sunday
Mostly clear in the morning with scattered clouds in the afternoon.
Sunday
Night
Mostly clear skies.
Sunday
Mostly clear in the morning with a few clouds in the afternoon.
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).