Friday starts cool across the region. Temperatures are similar to Thursday morning in many locations, but warming can be observed at upper-elevation weather stations on Mt Hood and Mt Rainier, where the impacts of an expanding ridge of high pressure will be felt first. A weak frontal system passes to our northwest into British Columbia on Friday. This is bringing some isolated rain/snow showers to the Washington Coast and the western Olympics. This is likely to keep the chance for light rain or snow in the Mt Baker area into the early afternoon. Temperatures remain relatively cool around Mt. Baker, so snow levels are unlikely to rise above 4,000 ft.
In other areas, expect partly to mostly cloudy skies to start the day, with clearing skies through the morning, transitioning to mostly sunny skies as the day progresses. Freezing levels rise from around 3000 ft in most areas early Friday up to 7500 ft in the south and 5000-6000 ft in the central Washington Cascades.
The expanding ridge of high pressure amplifies on Friday night, pushing any lingering clouds and precipitation near the Canadian border even further north. Temperatures will cool off in valley locations thanks to clear skies and light winds, but the freezing level keeps climbing overnight. The ridge reaches peak strength heading into the weekend, bringing sunny weather and light winds on Saturday. Temperatures will rise into the 50s for many mountain locations at 5,000 ft above sea level, as freezing levels rise to around 9,000-11,000 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
Partly cloudy in the northern and eastern Olympics with isolated rain or snow showers for the western Olympics. Cool start with warming temperatures throughout the day.
Friday
Night
Mostly clear skies. Mild.
Friday
Mostly cloudy with periods of light rain or snow, potentially ending during the afternoon.
Friday
Night
Partly cloudy to start, then clearing skies.
Friday
Mostly cloudy in the morning, transitioning to mostly sunny by late afternoon.
Friday
Night
Mostly clear skies. Mild.
Friday
A few low clouds to start, then becoming mostly sunny.
Friday
Night
Mostly clear skies. Mild.
Friday
Mostly cloudy to start, then becoming mostly sunny in the afternoon. Light ridgeline and W wind at the Pass.
Friday
Night
Mostly clear skies. Mild. Light ridgeline and W wind at the Pass.
Friday
Mostly cloudy to start, then becoming mostly sunny in the afternoon. Light ridgeline and W wind at the Pass.
Friday
Night
Mostly clear skies. Mild. Light ridgeline and W wind at the Pass.
Friday
Mostly cloudy to start, then becoming mostly sunny.
Friday
Night
Clear skies.
Friday
Mostly cloudy to start, then becoming mostly sunny.
Friday
Night
Clear skies.
Friday
A few clouds to start, then becoming mostly sunny.
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).