Gradually increasing WNW flow ushers in a pattern shift this weekend. Light rain and snow focus on the west slopes of the central and northern Cascades today with some weak convergence possible from Highway 2 to the mountain loop. Precipitation increases slightly in the afternoon with minor spillover into the immediate lee of the Cascade Crest. Expect 1-3" of snow above the 3000-3500 rain/snow line. 15-20 mph W ridgeline winds will focus on areas near and east of the Cascade Crest with strong gusts at times.
Saturday night, an upper trough begins to slide down the British Columbia Coastline. Light snow rain and snow continue to gradually increase and expand into the Mt Rainier area, perhaps becoming moderate by morning. Although temperatures cool aloft, subtle low-level warming raises the snow lines to around 3500-4000 ft in the central Cascades.
The cold front approaches from the NW on Sunday, bringing increasing moderate to heavy snow for the Washington Cascades. Ridgeline winds increase into the moderate to strong range with extreme gusts likely east of the Cascades. Snow totals above the rain/snow line should be in the 10-20 inch range for the west slopes of the Washington Cascades by the end of the day 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
Cloudy with a chance of light rain and snow from late morning onwards.
Saturday
Night
Periods of light rain and snow. Ridgeline winds become moderate in the afternoon.
Saturday
Light rain and snow. Light to moderate ridgeline winds.
Saturday
Night
Night: Increasing light rain and snow, becoming moderate by morning. Moderate ridgeline winds.
Saturday
Light rain and snow with weak convergence. Light to moderate ridgeline winds.
Saturday
Night
Increasing light rain and snow, becoming moderate by morning. Moderate ridgeline winds.
Saturday
Cloudy with a chance of chance of some very light rain or snow on the west side of
Saturday
Night
Light to moderate ridgeline wind speeds are higher near the Cascade Crest.
Saturday Night: Increasing light rain and snow, becoming moderate by morning. Moderate ridgeline winds.
Saturday
Periods of light rain and snow with weak convergence. Light to moderate ridgeline and light W wind at the Pass.
Saturday
Night
Increasing light rain and snow, becoming moderate in the early morning hours. Moderate ridgeline and mostly light W wind at the Pass.
Saturday
Periods of light rain and snow. Light to moderate ridgeline and light W wind at the Pass.
Saturday
Night
Increasing light rain and snow, becoming moderate in the early morning hours. Moderate ridgeline and mostly light W wind at the Pass.
Saturday
Mostly cloudy with an increasing chance of light rain or snow near the Cascade Crest in the afternoon. Increasing ridgeline winds with strong gusts.
Saturday
Night
Increasing light rain and snow. Moderate ridgeline winds with strong gusts.
Saturday
Mostly cloudy with an increasing chance of light rain or snow near the Cascade Crest in the afternoon. Increasing ridgeline winds with strong gusts.
Saturday
Night
Increasing light rain and snow. Moderate ridgeline winds with strong gusts.
Saturday
Mostly cloudy. Moderate ridgeline winds
Saturday
Night
Cloudy. Moderate ridgeline winds with strong gusts.
Saturday
Mostly sunny in the morning, then obscured skies or filtered sunshine in the afternoon. Moderate ridgeline winds, strong gusts.
Saturday
Night
Cloudy. Moderate ridgeline winds with strong gusts.
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).