An unusually persistent January high pressure remains parked off the Oregon Coast on Wednesday. A very subtle disturbance sliding southward has already exited the region with a few high clouds early Wednesday morning. In its wake, a few weather stations in the central Washington Cascades (Mission Ridge, Alpental summit, and Dirtyface) are experiencing moderate winds, which should descend into the light range by the afternoon. A strong low-level inversion exists this morning. Increasing E flow should continue to usher the low-level cold air through the mountain gaps, but daytime mixing should help these low-level temperatures rise above freezing. E flow peaks late Wednesday night into Thursday morning before decreasing on Thursday. The high pressure shifts eastward and should be centered over our region by late Thursday, resulting in slightly higher freezing levels, very light winds, and a very strong lid producing strong low-level inversions and dense low clouds that may not dissipate by the afternoon. Freezing levels should be 7500-10000 ft throughout the next 36 hours, except at Washington Pass where the depth of the low-level inversion will be thicker.
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. Low cloud in lowlands and deep valleys. Inversion up to around 4000 ft mixing out by the afternoon.
Wednesday
Night
Mostly clear with slightly increasing high clouds. Low clouds and inversion redeveloping in the lowlands and valleys.
Wednesday
Mostly sunny. Low cloud in lowlands and deep valleys. Inversion up to around 4500 ft mixing out by the afternoon.
Wednesday
Night
Mostly clear with slightly increasing high clouds. Low clouds and inversion redeveloping in the lowlands and valleys.
Wednesday
Mostly sunny. Low cloud in lowlands and deep valleys. Inversion up to around 4000 ft mixing out by the afternoon.
Wednesday
Night
Mostly clear with slightly increasing high clouds. Low clouds and inversion redeveloping in the lowlands and valleys.
Wednesday
Mostly sunny. Low cloud in lowlands and deep valleys. Inversion up to around 4000 ft mixing out by the afternoon.
Wednesday
Night
Mostly clear with slightly increasing high clouds. Low clouds and inversion redeveloping in the lowlands and valleys.
Wednesday
Mostly sunny. Low cloud in lowlands and deep valleys. Inversion up to around 4000 ft mixing out by the afternoon. Increasing light E winds at the Pass.
Wednesday
Night
Mostly clear with slightly increasing high clouds. Low clouds and inversion redeveloping in the lowlands and valleys. Increasing light to moderate E winds at the Pass.
Wednesday
Mostly sunny. Low cloud in lowlands and deep valleys. Strong low-level inversion mixing out by the afternoon. Increasing light E winds at the Pass.
Wednesday
Night
Mostly clear with slightly increasing high clouds. Low clouds and inversion redeveloping in the lowlands and valleys. Increasing light to moderate E winds at the Pass.
Wednesday
Mostly sunny. Low cloud in lowlands and deep valleys. Strong inversion.
Wednesday
Night
Mostly clear with slightly increasing high clouds. Low clouds and inversion redeveloping in the lowlands and valleys.
Wednesday
Mostly sunny. Low cloud in lowlands and deep valleys. Inversion up to around 4000 ft mixing out by the afternoon.
Wednesday
Night
Mostly clear with slightly increasing high clouds. Low clouds and inversion redeveloping in the lowlands and valleys.
Wednesday
Mostly sunny. Low cloud in lowlands and deep valleys. Inversion up to around 4000 ft mixing out by the afternoon.
Wednesday
Night
Mostly clear with slightly increasing high clouds. Low clouds and inversion redeveloping in the lowlands and valleys.
Wednesday
Mostly sunny. Low cloud in lowlands and deep valleys. Inversion up to around 4000 ft mixing out by the afternoon.
Wednesday
Night
Mostly clear with slightly increasing high clouds. Low clouds and inversion redeveloping in the lowlands and valleys.
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).