A subtle upper trough slides east on Saturday. Increasing WNW flow in the wake of the trough brings light snow showers throughout the region and weak convergence to the central Washington Cascades. High clouds streaming in ahead of the next system will make sun breaks unlikely by the afternoon. Temperatures remain cool with snow levels below pass levels. Expect 1-4" of snow today across the west slopes of the Cascades and passes.
An atmospheric river initially aimed at the central British Columbia coastline begins to spread increasing rain and snow into our region Saturday night. Snow levels remain low (1500-2500 ft), but will begin to rise toward morning. Precipitation will start off light to moderate and will end the night moderate to heavy with 3-10" of snow expected for much of the west slopes of the Washington Cascades overnight.
Expect moderate to heavy rain and snow on Sunday. Snow levels rise rapidly early Sunday morning with snow changing to rain at Snoqualmie Pass at that time. Elevations above 4000 ft should expect significant snow accumulations.
W winds should gradually increase Saturday through Saturday night and maintain in the moderate to occasionally strong range on Sunday.
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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Saturday
Light snow showers.
Saturday
Night
Increasing light rain and snow.
Saturday
Light snow showers.
Saturday
Night
Increasing moderate rain and snow.
Saturday
Light snow showers.
Saturday
Night
Increasing moderate to heavy rain and snow.
Saturday
Light snow showers.
Saturday
Night
Increasing moderate rain and snow at Paradise and White Pass; increasing light rain and snow at Crystal.
Saturday
Light snow showers. Light W wind at the Pass.
Saturday
Night
Increasing moderate rain and snow. Light to occasionally moderate W wind at the Pass.
Saturday
Light snow showers. Light to occasionally moderate W wind at the Pass.
Saturday
Night
Increasing moderate to heavy rain and snow. Light tomoderate W wind at the Pass.
Saturday
Light snow showers.
Saturday
Night
Increasing light snow.
Saturday
Light snow showers.
Saturday
Night
Increasing moderate rain and snow.
Saturday
Very light snow showers, mainly near the Cascade Crest.
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).