The Pacific Northwest remains in the final 24-36 hours of a cold, snowy pattern. An upper-level trough shifts east of the region on Thursday as a ridge builds offshore, switching upper-level winds NWerly. Scattered showers continue to move into the region on brisk W ridgeline winds, which will accelerate in some areas near and east of the Cascade Crest. Snow showers are becoming less convective and less intense as the atmosphere gradually becomes more stable. Expect less spillover onto the E slopes of the Cascades as a result. Some convergence potential exists from Skagit County down to I-90, but the location and timing of any relative weak convergence enhancement remains uncertain. Snow levels remain low, in the 1000-2000 ft range.
Snow shower activity becomes mostly light Thursday night as snow levels rise to 1500-2500 ft.
The expanding ridge cuts off lingering light precipitation from south to north on Friday. Expect sunshine by Friday afternoon and increasing sunshine for Mt Hood as freezing levels rise to 6000 ft. Conditions will be cloudier and cooler, with light snow showers or snow flurries, mainly during the morning hours, for areas further north. Expect sun breaks in these areas during the afternoon as snow levels rise to around 3000 ft.
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
Light low-density snow showers.
Thursday
Night
Light snow showers confined to western Olympics with mostly cloudy skies and snow flurries further east.
Thursday
Light to moderate low-density snow showers.
Thursday
Night
Light low-density snow showers.
Thursday
Moderate low-density snow showers and convergence enhancement. Periods of moderate ridgeline winds near the Cascade Crest.
Thursday
Night
Decreasing light to moderate low-density snow showers.
Thursday
Light to moderate low-density snow showers. Moderate ridgeline winds near the Cascade Crest.
Thursday
Night
Decreasing light to occasionally moderate low-density snow showers. Periods of moderate ridgeline winds near the Cascade Crest.
Thursday
Mostly light low-density snow showers with periods of moderate convergence possible. Light to moderate ridgeline and light W wind at the Pass.
Thursday
Night
Mostly light low-density snow showers. Decreasing mostly light ridgeline and W wind at the Pass.
Thursday
Moderate low-density snow showers. Moderate ridgeline and light to moderate W wind at the Pass.
Thursday
Night
Light to moderate low-density snow showers. Decreasing moderate ridgeline and mostly light W wind at the Pass.
Thursday
Light low-density snow showers. Light to 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).