A ridge of high pressure continues to build into the region from west through Saturday. The upper-level high pressure extends down to the surface. The surface manifestation of the high continues to drive light to moderate W flow through the mountain gaps. The flow pattern banks traps low-level moisture against the west slopes of the Washington Cascades, forming thick low-level clouds and some very light drizzle or snow flurries at times through Friday night. Given that most areas will remain dry, this forecast predicts freezing levels rather than snow levels. Freezing levels should rise to 4500-5500 ft this afternoon. The warmest temperatures should occur in areas with fewer clouds, along the east slopes of the Cascades, Mt. Hood, and in the Olympics.
Most areas will not see freezing levels fall Friday night as the high pressure continues to work into the region. Mt. Hood may see freezing levels rise slightly overnight. Changes in cloud distribution should be minimal, but some high clouds may begin to move into northern Washington State in the early morning hours.
The high pressure flattens on as it continues to expand into our region through mid-day Saturday. High and mid-level clouds should increase over parts of Washington State ahead of the next system arriving on NW flow, but moisture should hold off until Saturday night. In the southern parts of the forecast region, temperatures will continue to climb with freezing levels likely topping 9000 ft for Mt. Hood on Saturday afternoon.
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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Friday
Mostly clear.
Friday
Night
Mostly clear to start with high clouds increasing.
Friday
Mostly cloudy with a chance of drizzle/snow flurries.
Friday
Night
Mostly cloudy with a chance of drizzle/snow flurries.
Friday
Mostly cloudy with a chance of drizzle/snow flurries.
Friday
Night
Mostly cloudy with a chance of drizzle/snow flurries.
Friday
Mostly cloudy with a chance of drizzle/snow flurries.
Friday
Night
Partly cloudy.
Friday
Mostly cloudy with a chance of drizzle/snow flurries. Light to occasionally moderate W wind at the Pass.
Friday
Night
Mostly cloudy with a chance of drizzle/snow flurries. Light to occasionally moderate W wind at the Pass.
Friday
Mostly cloudy with a chance of drizzle/snow flurries. Increasing light to moderate W wind at the Pass.
Friday
Night
Mostly cloudy with a chance of drizzle/snow flurries. Decreasing light to moderate W wind at the Pass.
Friday
Partly cloudy.
Friday
Night
Partly cloudy.
Friday
Mostly cloudy to start, then decreasing clouds near the Cascade Crest. Mostly sunny further east.
Friday
Night
Partly cloudy.
Friday
Mostly cloudy to start, then decreasing clouds near the Cascade Crest. Mostly sunny further east.
Friday
Night
Friday
Scattered clouds mostly on the west slopes of Mt. Hood with clearing skies on the east side.
Friday
Night
Scattered clouds mostly on the west slopes of Mt. Hood with mostly clear skies on the east side.
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).