An elongated upper low continues to bring cool and unsettled weather to the western U.S. More locally, a surface low has formed over eastern Washington and drifts eastward on Friday. Upper-level SE winds in that area drift the moisture associated with this low into the northern Cascades, particularly around Washington Pass, during the day. This moisture dissipates during the evening hours. Meanwhile, expect low-level W winds to increase through the Cascade gaps, east slopes, and Mt Hood areas as the broad upper low shifts eastward. These winds should become moderate along exposed ridgelines and peak Friday evening before gradually decreasing overnight. These W winds focus very light shower activity on the west slopes of the Cascades with a few more breaks of clear skies, particularly along the east slopes.
On Saturday, a trough approaches the coastline, bringing increasing light rain and snow showers and another round of moderate W ridgeline winds.
Extensive cloud cover continues to dampen the diurnal temperature signal across the region, but expect snow levels in the 2000-3500 ft range.
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
A chance of light rain or snow showers. Mostly cloudy skies to start, then becoming partly sunny by the afternoon.
Friday
Night
Mostly clear in the evening, then becoming mostly cloudy overnight.
Friday
Mostly cloudy with a chance of light rain or snow, particularly east of Mt Baker.
Friday
Night
Partly to mostly cloudy.
Friday
Mostly cloudy with periods of light rain or snow.
Friday
Night
Mostly cloudy with scattered very light rain or snow showers.
Friday
Mostly cloudy with scattered light rain or snow showers.
Friday
Night
Mostly cloudy with scattered very light rain or snow showers.
Friday
Mostly cloudy with periods of light rain or snow. Light ridgeline and W wind at the Pass.
Friday
Night
Partly cloudy with scattered very light rain or snow showers. Light ridgeline and W wind at the Pass.
Friday
Mostly cloudy with periods of light rain or snow. Increasing light to moderate ridgeline and W wind at the Pass.
Friday
Night
Partly to mostly cloudy with scattered very light rain or snow showers. Moderate ridgeline and light to moderate W wind at the Pass.
Friday
Mostly cloudy with periods of light rain or snow. Moderate ridgeline winds.
Friday
Night
Partly cloudy with scattered very light rain or snow showers. Decreasing light to moderate ridgeline winds.
Friday
Mostly cloudy with periods of light rain or snow. Increasing light to moderate ridgeline winds.
Friday
Night
Partly cloudy with isolated very light rain or snow showers. Moderate ridgeline winds.
Friday
Mostly cloudy with periods of very light rain or snow. Light to moderate ridgeline winds.
Friday
Night
Partly cloudy with isolated very light rain or snow showers. Light to moderate ridgeline winds.
Friday
Mostly cloudy with light rain or snow showers increasing by the afternoon. Moderate ridgeline winds.
Friday
Night
Mostly cloudy with light rain or snow showers. Moderate ridgeline winds and 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).