A cold and windy storm system continues to impact the Pacific Northwest on Saturday. Post-frontal snow showers continue across the region with the heaviest snowfall in the central Washington Cascades where a broad band of convergence continues to bring a swath of moderate snowfall from Stevens Pass south to Snoqualmie. As winds shift from W to WNW, that convergence should shift southward and focus more exclusively upon Snoqualmie Pass after 8 AM. By around noon, we expect the convergence band to dissipate, but not before bringing an additional 1-3" of snow to Stevens Pass and 3-5" to Snoqualmie Pass. Temperatures have cooled further behind the front, leaving snow levels around 500-1000 ft this morning, with accumulating snows above 1500 ft. With mostly cloudy skies along the west slopes of the Cascades, temperatures shouldn't rise out of the 20s at mid and upper elevations today. Winds continue to be a major story with this system. Strong ridgeline winds peak early Saturday morning for the mountain gaps and east slopes of the Cascades with very strong winds in the Mt. Hood area. In some cases, sustained winds have been moderate, but gusts are in the 40-50 mph range. Winds should very slowly decrease during the day.
After early evening snow flurries in some areas, a clearing trend takes place overnight. With a cold air mass in place and much lighter winds, expect strong radiational cooling and low overnight temperatures.
Sunday starts cold, but with plenty of sunshine, high temperatures should rebound nicely, but remain below season norms.
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 tapering to flurries by afternoon. Partly cloudy.
Saturday
Night
Partly cloudy in the evening, then becoming mostly clear.
Saturday
Decreasing light snow showers.
Saturday
Night
Partly cloudy in the evening, then becoming mostly clear.
Saturday
Convergence tapering and shifting southward in the southern part. Otherwise, decreasing light snow showers. Gradually decreasing moderate ridgeline winds with strong to extreme gusts.
Saturday
Night
Partly cloudy in the evening, then becoming mostly clear.
Saturday
Decreasing light snow showers. Decreasing strong ridgeline winds becoming moderate during the afternoon.
Saturday
Night
Mostly cloudy with light snow flurries in the evening, then partial clearing after midnight.
Saturday
Convergence over Stevens in the early morning hours, then shifting southward leaving decreasing light snow showers. Gradually decreasing moderate ridgeline winds with very strong gusts. Decreasing moderate W wind at the Pass.
Saturday
Night
Partly cloudy in the evening, then becoming mostly clear.
Saturday
Convergence likely until late morning, then decreasing very light snow showers during the afternoon. Gradually decreasing moderate to strong ridgeline winds with very strong to extreme gusts. Decreasing moderate to strong winds at the Pass.
Saturday
Night
Partly cloudy in the evening, then becoming mostly clear.
Saturday
Very light snow showers.
Saturday
Night
Partly cloudy in the evening, then becoming mostly clear.
Saturday
Convergence spillover during the morning hours, then very light snow showers with partial sunshine in the afternoon. Strong ridgeline winds with very strong to extreme gusts.
Saturday
Night
Partly cloudy in the evening, then becoming mostly clear.
Saturday
Decreasing very light snow showers. Decreasing moderate to strong ridgeline winds with very strong gusts.
Saturday
Night
Mostly cloudy with light snow flurries in the evening, then partial clearing after midnight.
Saturday
Decreasing light to moderate snow showers.
Saturday
Night
Mostly cloudy with light snow flurries in the evening, then partial clearing after midnight.
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).