An upper low off the Alaskan Panhandle continues to drift southward toward our region. On Friday, a subtle disturbance ahead of the upper low will bring some cloud cover and a slight chance of a rain or snow shower to Washington Cascades and Olympics during the afternoon. It will be difficult to predict where any very light precipitation might occur. WSW winds should be light at ridgelines in most areas but remain moderate in the Mt. Hood region. Temperatures should be slightly cooler than Thursday with the disturbance bringing a mix of low clouds to the west of the Cascade Crest and high cloud across the region.
High clouds gradually increase overnight as the upper low approaches Friday night. Very subtle ridging ahead of the low allows milder temperatures to work into the region through Saturday morning. Expect mild temperatures Friday night with a poor refreeze possible at lower elevations given the cloud cover.
A band of increasing light rain and snow arrive in the northern Washington Cascades and Olympics by Saturday afternoon with the primary low drifting southward along the central British Columbia coastline by late in the day. An inch or two of snow might be expected above 5000 ft in the Mt. Baker area.
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
Partly cloudy with a mix of low clouds and thin high clouds.
Friday
Night
Partly to mostly cloudy.
Friday
Mostly cloudy with a mix of low clouds and thin high clouds.
Friday
Night
Partly to mostly cloudy.
Friday
Partly cloudy with a mix of low clouds and thin high clouds.
Friday
Night
Partly to mostly cloudy.
Friday
A mix of filtered sunshine and low clouds.
Friday
Night
Partly to mostly cloudy.
Friday
Partly cloudy. Light W wind at the Pass.
Friday
Night
Partly to mostly cloudy. Light W wind at the Pass.
Friday
Partly cloudy with a mix of thin high clouds and some low clouds. Light W wind at the Pass.
Friday
Night
Partly to mostly cloudy. Light W wind at the Pass.
Friday
Partly to mostly sunny with primarily high clouds.
Friday
Night
Friday
Increasing partial cloud cover.
Friday
Night
Partly to mostly cloudy.
Friday
Mostly sunny start with thickening high clouds.
Friday
Night
Partly to mostly cloudy.
Friday
Partly cloudy in the morning, then becoming mostly cloudy as high-level clouds increase.
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).