A deep Pacific trough and associated surface low will slide over the region today maintaining light showers for areas near and west of the Cascade crest. Without a significant source of moisture for this system, precipitation totals should remain very modest. Onshore flow will keep low-level clouds banked up against the mountains and pushing into the passes. As the trough shifts overhead, the mid and upper atmosphere will dry significantly allowing skies to clear. This could result in mostly sunny skies along the eastern slopes of the Cascades by the afternoon.
A few lingering showers may hang around into the evening hours, but generally, the trend will be for clearing and drying. Low clouds west of the crest should start to break allowing for colder temperatures than we've seen recently. East of the crest, mostly clear skies may cause temperature inversions along with low clouds and valley fog to form by Friday morning.
A compact weak storm passes just off the Washington coast Friday. While this won't result in any precipitation for the mountains, it should keep just enough low-level moisture in place to form clouds along the western side of the Cascades. Areas closer to the Canadian border and east of the Crest should enjoy a beautiful sunny day with temperatures warming in the 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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Thursday
Mostly cloudy with isolated snow showers.
Thursday
Night
Partly cloudy with some clearing overnight.
Thursday
Cloudy with scattered light showers.
Thursday
Night
Cloudy with isolated showers in the evening. Then some clearing overnight.
Thursday
Cloudy with scattered light showers. A weak Puget Sound Convergence Zone may bring locally heavier rain and snow during the morning to areas between Hwy 2 and I90.
Thursday
Night
Cloudy with isolated showers in the evening. Then some clearing overnight.
Thursday
Cloudy is isolated showers. Light to moderate NW winds in the afternoon.
Thursday
Night
Mostly cloudy, with a few flurries possible. Some clearing possible overnight.
Thursday
Cloudy with isolated showers. Winds becoming WNW light to moderate.
Thursday
Night
Cloudy with isolated showers possible in the evening. Then drying with some clearing possible. Light NW winds.
Thursday
Cloudy with isolated showers. Winds becoming WNW light to moderate.
Thursday
Night
Cloudy with isolated showers in the evening. Then drying with some clearing possible. Light to moderate NW winds.
Thursday
Mostly cloudy with isolated showers possible. Becoming partly to mostly sunny in the afternoon.
Thursday
Night
Partly to mostly clear with some valley fog and low clouds.
Thursday
Mostly cloudy with isolated showers near the crest. Becoming partly to mostly sunny. Light to moderate W winds becoming NW.
Thursday
Night
Partly to mostly clear with some valley fog and low clouds.
Thursday
Mostly cloudy with a few flurries possible near Hwy 410. Light to moderate W winds. Clearing skies possible in the afternoon.
Thursday
Night
Partly to mostly clear with some valley fog and low clouds. Light to moderate NW winds becoming calm overnight.
Thursday
Mostly cloudy with mid to high clouds. Light NW winds becoming moderate 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).