Satellite imagery and mountain weather stations show a generally clear, cool, and calm start to the day for most of our trailheads. Strong temperature inversions are keeping the valleys and passes chillier than surround ridgelines. At mid and upper elevations much warmer air has already made its way into the Pacific Northwest. As a result, temperatures should rise rapidly over the morning hours as the inversions quickly break. Highs for many of our mountain locations should easily reach the mid 40's with some sites topping 50 degrees. A high-pressure ridge situated over the region should provide us with mostly sunny skies, warm temperatures, and generally light winds. Clouds originating from a storm system off the coast of British Columbia will slowly make their way inland today. High clouds will be most prevalent in areas further north and west like Mt Baker, the Mt Loop Highway, and the Olympics. However, nearly all locations should see at least some periods of thin clouds by the afternoon.
The approaching low-pressure continues to push against the ridge as we head into the overnight hours. This should result in a blanket of thin clouds and increasing ridgeline winds. While temperature inversions should return, they don't appear near as strong and many locations could remain above freezing. Overnight most mountain sites should see partly to mostly cloudy skies, mild temperatures, and moderate to strong winds.
On Thursday, the shoving match between the high-pressure and approaching storm continues. As the ridge shifts further east and begins to flatten, slightly cooler air and increasing clouds finally push their way into the Northwest. However, nearly all of the precipitation deflects north into Canada and we're left with dry, cloudy, and windy weather.
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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Wednesday
Mostly sunny and warm with high thin clouds increasing.
Wednesday
Night
Mostly clear and mild with high thin clouds. Moderate SW winds increasing.
Wednesday
Mostly sunny in the morning with increasing high clouds. SW winds increasing and becoming moderate.
Wednesday
Night
Mostly cloudy and mild. Moderate to strong SSW winds.
Wednesday
Mostly sunny with high clouds increasing during the day.
Wednesday
Night
Partly cloudy with high clouds. Moderate SW winds increasing.
Wednesday
Mostly sunny and warm. Periods of high clouds.
Wednesday
Night
Mostly clear and mild. Moderate to strong SW winds.
Wednesday
Mostly sunny and warm. High thin clouds increasing in the afternoon. Light E flow.
Wednesday
Night
Partly cloudy and mild. High clouds. Moderate ridgeline winds.
Wednesday
Sunny and warm. Increasing high clouds possible in the afternoon. Light E flow.
Wednesday
Night
Mostly clear and mild. High clouds possible. Moderate ridgeline winds.
Wednesday
Mostly sunny and warm. Periods of high clouds.
Wednesday
Night
Mostly clear and mild with temperature inversions. Moderate SW winds.
Wednesday
Mostly sunny and warm. Periods of high clouds.
Wednesday
Night
Mostly clear and mild. Moderate SW winds.
Wednesday
Sunny and warm. Periods of high clouds possible in the afternoon.
Wednesday
Night
Mostly clear and mild. Moderate SW winds becoming strong.
Wednesday
Sunny and warm. Periods of high clouds in the afternoon. SW winds increasing and becoming moderate.
Wednesday
Night
Mostly clear and mild. High clouds possible. Strong SW 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).