We're on the backside of a broad upper trough that stretches over most of the contiguous US and Canada with NW flow aloft. The pattern will change very little over the next 48 hours. We expect light and scattered snow showers for the West Central and West North zones to increase this afternoon and wax and wane through Friday morning for a few inches every 12hrs, especially the western parts of these zones. Snow showers should be lighter and less impactful for Stevens and Snoqualmie Passes. Further south and along the east slopes of the Cascades, expect low clouds to break up near the crest (with the exception for East North where an increase in cloud cover is expected this afternoon(. Freezing levels will slowly warm over the next 2 days, with southern areas warming more on the periphery of the upper trough.
The bigger story will be the moderate to occasionally strong WNW ridgeline winds. Winds have increased faster than expected overnight and should hold steady on Wednesday. Winds will increase further on Thursday, becoming strong in many areas. If you're planning to head to upper elevations, expect to battle WNW winds over the next 2 days.
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
Partly to mostly cloudy in the morning, then mostly cloudy with scattered light snow showers in the afternoon. Moderate ridgeline winds, stronger at upper elevations.
Wednesday
Night
Mostly cloudy with scattered light snow showers. Moderate ridgeline winds, stronger at upper elevations.
Wednesday
Cloudy with a chance of light snow showers in the morning, showers increasing in the afternoon and occasionally moderate western part of the zone. Moderate ridgeline winds, stronger at upper elevations.
Wednesday
Night
Cloudy with scattered light snow showers, occasionally moderate western part of the zone. Moderate ridgeline winds, stronger at upper elevations.
Wednesday
Cloudy with a chance of light snow showers in the morning, showers increasing in the afternoon and occasionally moderate western part of the zone. Moderate ridgeline winds, stronger at upper elevations.
Wednesday
Night
Cloudy with scattered light snow showers, occasionally moderate western part of the zone. Moderate ridgeline winds, stronger at upper elevations.
Wednesday
Cloudy with a slight chance of a snow shower western part of the zone. Mostly cloudy with sunbreaks eastern part of the zone. Moderate ridgeline winds, stronger at upper elevations.
Wednesday
Night
Cloudy western part of the zone, partly to mostly cloudy eastern part of the zone. Moderate ridgeline winds, stronger at upper elevations.
Wednesday
Cloudy with scattered light snow showers in the afternoon. Moderate W Pass level and ridgeline winds, stronger at upper elevations.
Wednesday
Night
Cloudy with occasional light snow showers. Moderate W Pass level and ridgeline winds, stronger at upper elevations.
Wednesday
Cloudy with scattered light rain and snow showers in the afternoon. Moderate W Pass level and ridgeline winds, stronger at upper elevations.
Wednesday
Night
Cloudy with occasional light snow showers. Moderate W Pass level and ridgeline winds, stronger at upper elevations.
Wednesday
Cloudy near the crest in the morning, clearer further east. Increasing clouds in the afternoon. Moderate to occasionally strong ridgeline winds.
Wednesday
Night
Cloudy with occasional light snow showers near the Cascade crest. Moderate to occasionally strong ridgeline winds.
Wednesday
Mostly cloudy near the crest in the morning, clearer further east. Increasing clouds in the afternoon north of I-90. Moderate to strong ridgeline winds.
Wednesday
Night
Partly to mostly cloudy near the crest, mostly clear to the east. Moderate to strong ridgeline winds.
Wednesday
Partly to mostly cloudy near the crest in the morning, clearing just east of the crest. Increasing clouds in the afternoon.Moderate to strong ridgeline winds.
Wednesday
Night
Partly to mostly cloudy near the crest, mostly clear to the east. Moderate to strong ridgeline winds.
Wednesday
Mostly sunny with low clouds on the western part of the mountain. Moderate to occasionally strong ridgeline winds.
Wednesday
Night
Mostly clear with some low clouds on the western part of the mountain. Moderate to occasionally strong 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).