The weather will deteriorate Friday as a strong winter storm approaches the areas. Expect increasing winds and developing snow showers in the afternoon.
A low-pressure system off the coast is already spinning moisture up from the south into the Olympics and Puget Sound this morning. Showers will continue to work their way further inland throughout the day. Look for winds to turn more southerly and become gusty as the storm draws closer.
The bulk of the precipitation arrives in the evening hours. With southerly flow, this storm will favor areas like Mt Baker, Crystal Mountain, Mt Rainier, and locations along the east side of the range such as Mission Ridge. While not a major storm event, the combination of the gusty winds and periods of moderate precipitation should lead to a stormy night in the mountains.
Most places should see a brief break in the action on Satruday morning before a trailing cold front reinvigorates precipitation in the afternoon. While most trailhead locations should see snow throughout this storm, a shift from east to west flow late Saturday could bring a short period of rain to Snoqualmie Pass.
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
Stormy, particularly in the southern and western Olympics. Southerly winds becoming strong and gusty.
Friday
Night
Stormy, particularly in the southern and western Olympics. Strong and gusty southerly winds.
Friday
Cloudy with occasional showers, mainly in the afternoon. Moderate but gusty southerly winds.
Friday
Night
Stormy with periods of moderate to occasionally heavy precipitation. Moderate to strong and gusty S winds.
Friday
Cloudy with occasional light showers. Light to moderate but gusty winds.
Friday
Night
Ran and snow. Light to moderate but gusty southerly winds.
Friday
Cloudy with a few snow showers. Moderate but gusty southerly winds.
Friday
Night
Snow. Heaviest near Crystal Mt, Mt Rainier, and Mount Saint Helens. Showers near White Pass and Mt Adams. Moderate but gusty SSE winds turning SSW.
Friday
Cloudy with a few light showers in the afternoon. SE ridgeline winds becoming light to moderate. Light E flow at Pass level.
Friday
Night
Cloudy with snow showers. Light to moderate SE winds decreasing slightly. Light East flow at Pass level.
Friday
Cloudy with a few light showers mainly in the afternoon. SE ridgeline winds becoming moderate and gusty. Light east flow at pass level.
Friday
Night
Cloudy with snow showers. Moderate and gusty SE winds decreasing and turning S. E flow at pass level.
Friday
Cloudy with a few light snow showers in the afternoon. Light to moderate S winds.
Friday
Night
Cloudy with snow showers, heaviest in the eastern portion of the zone. Moderate and gusty SE winds decreasing and turning S.
Friday
Cloudy with snow showers mainly in the afternoon. Winds increasing and becoming moderate to strong and gusty S.
Friday
Night
Snow, heaviest in the Wenatchee Mts and the southern side of the Enchantment Range. Moderate to strong and gusty S winds decreasing slightly and turning SW.
Friday
Cloudy with a few snow showers in the afternoon. Winds becoming S moderate to strong and gusty.
Friday
Night
Cloudy with snow heaviest along the eastern edge of the mountains. Moderate to strong and gusty S winds decreasing slightly.
Friday
Cloudy with snow developing mainly in the afternoon. Moderate to strong and gusty SW winds.
Friday
Night
Snow. Heaviest in the evening. Moderate to strong and gusty SW 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).