A stronger closed low tracks toward the Northern California coastline, shunting moisture northward, associated with an original weakening low-pressure center. Friday starts with thin high clouds over the northern portions of the forecast region, with mid-level clouds and perhaps an isolated rain shower over the southern portions. These thickening clouds should spread northward as the day progresses. Friday starts very mild with temperatures general 2-7F warmer than Thursday morning. However, cloud cover and slight cooling aloft mean that 5000 ft temperatures might top out around 5F cooler than on Thursday. Expect light, variable, or S-to-E ridgeline winds, with breezier conditions near the Cascade Crest.
Banded showers of mostly light rain and higher elevation spreads into the southern half of the forecast region Friday evening, increasing somewhat and expanding northward overnight as light WSW ridgleline winds develop.
Saturday will be cloudy with a band of widespread light precipitation. A band of light rain and higher-elevation snow lifts northward across the region, focusing on areas near and west of the Cascade Crest, with snow levels hovering around 6000 ft.
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
Thin high clouds gradually lowering and thickening from late morning onwards. Warm.
Friday
Night
Cloudy with a chance of light rain or higher elevation snow, mainly in the early morning hours.
Friday
Thin high clouds gradually lowering and thickening in the afternoon. Warm.
Friday
Night
Cloudy with a chance of light rain or higher elevation snow, mainly in the early morning hours.
Friday
Thin high clouds gradually lowering and thickening in the afternoon. Warm.
Friday
Night
Cloudy with a chance of light rain or higher elevation snow, mainly in the early morning hours.
Friday
Mostly cloudy skies. Warm.
Friday
Night
Mostly cloudy with increasing periods of light rain or higher elevation snow.
Friday
High clouds to start, then clouds lowering and gradually thickening from mid-morning onward. Light ridgeline winds. E winds at the Pass switch W by late morning.
Friday
Night
Mostly cloudy in the evening with a few rain or higher elevation snow showers overnight. Light ridgeline and W wind at the Pass.
Friday
High clouds to start, then clouds lowering and gradually thickening from mid-morning onward. Light to occasionally moderate ridgeline winds. E winds at the Pass switch W by late morning.
Friday
Night
Mostly cloudy in the evening with a few rain or higher elevation snow showers overnight. Light ridgeline and W wind at the Pass.
Friday
Thin high clouds gradually lowering and thickening in the afternoon. Warm.
Friday
Night
Partly cloudy in the evening, becoming mostly cloudy overnight with chances for light rain or higher-elevation snow.
Friday
Thin high clouds gradually lowering and thickening from mid-morning onward. Warm.
Friday
Night
Mostly cloudy, with increasing chances of light rain or higher-elevation snow showers.
Friday
Thin high clouds gradually lowering and thickening. Warm.
Friday
Night
Mostly cloudy, with increasing chances of light rain or higher-elevation snow showers.
Friday
Mostly cloudy with a slight chance of rain or higher elevation snow late in the day.
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).