The Pacific Northwest will sit between the two branches of a split jet stream Thursday. Without much available moisture, the atmosphere can't muster more than a few isolated showers along some of the higher terrain of the Cascades and western Olympics. Places like Mt Hood, Mt St Helens, and Mt Baker could see the most snow, but it shouldn't amount to more than a dusting. In general, Thursday should be dry and cool for most locations. Expect mostly sunny skies in the morning to turn cloudier late in the day ahead of our next weather system.
The jet stream will refocus on our region this evening. Weak, warm frontal moisture drifts into the area overnight, gradually increasing rain and snow. There's not much to help the showers make their way further east. So, this first round primarily focuses on the west slopes of the Cascades and Olympics. Precipitation continues to increase Friday across the mountains as a low-pressure trough approaches the coast. While the heaviest rain and snow should hold off until overnight, expect the storm to begin to intensify later in the day.
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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Thursday
Mostly sunny with increasing clouds and a few showers along the W slopes of the Olympics.
Thursday
Night
Cloudy with increasing showers. Winds becoming SW light to moderate.
Thursday
Mostly sunny in the morning, becoming mostly cloudy in the afternoon. A few isolated showers possible late in the day.
Thursday
Night
Cloudy with showers increasing. Winds becoming SSW light to moderate.
Thursday
Partly sunny in the morning with increasing clouds. A stray shower possible later in the day.
Thursday
Night
Cloudy with showers increasing. Winds becoming SW light to moderate.
Thursday
Partly to mostly sunny, with increasing clouds in the afternoon. Isolated showers particularly for the southern volcanoes. Light to moderate W winds.
Thursday
Night
Cloudy with increasing showers. Winds becoming W moderate.
Thursday
Partly to mostly sunny in the morning with increasing clouds in the afternoon. W winds becoming light to moderate.
Thursday
Night
Cloudy with scattered showers. Light to moderate W winds.
Thursday
Partly to mostly sunny in the morning. Becoming cloudy in the afternoon with a very isolated shower possible. W winds becoming moderate.
Thursday
Night
Cloudy with increasing showers. Moderate W winds.
Thursday
Mostly sunny, becoming partly cloudy later in the day.
Thursday
Night
Partly to mostly cloudy with increasing high clouds. Light to moderate W winds.
Thursday
Becoming mostly sunny in the morning, with a few increasing clouds near the crest in the afternoon. Light to moderate NW winds turning W and increasing.
Thursday
Night
Cloud with a few isolated showers near the crest. Moderate W winds.
Thursday
Mostly sunny in the morning becoming partly to mostly cloudy in the afternoon. Light to moderate NW wind turning W and increasing.
Thursday
Night
Mostly cloudy with increasing high clouds. A few very isolated showers possible near the crest. Moderate W winds.
Thursday
Mostly cloudy with a few light showers throughout the day. Moderate W winds increasing in the afternoon.
Thursday
Night
Cloudy with scattered showers. Moderate to strong W winds becoming strong and gusty.
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).