Thursday will be very slightly milder than Wednesday. Temperatures start the day in the mid-20s through low 30s at most NWAC stations. The remnants of an upper low continue to rotate decreasing rain and snow shower activity in our region on Thursday. The focus of morning scattered showers will be on the southern Olympics and Mt Baker areas, driven by weak instability S winds. These winds were locally in the moderate range around Mt Baker early Thursday morning around Mt Baker but should decrease along with the shower activity, which becomes isolated or tapers off in the afternoon. S or W winds in other areas remain light. A ridge over the interior builds into the region, bringing partly cloudy skies by the afternoon along with 5000-6000 ft freezing levels.
Thursday night, weak ridging remains the dominant influence. The remnant closed low joins a broader upper low off the California Coastline. That low will be far enough away to allow skies to clear across most of our region overnight. Expect light ridgeline winds and some very light E winds through the gaps.
On Friday, freezing levels start the day in the 2500-4500 ft range. Weak ridging continues, allowing for more mostly sunny skies. Freezing levels rise to 5000-7000 ft in the afternoon. Light W winds gradually increase as the ridge flattens, beginning the gradual transition to a pattern shift with WNW flow and weather for the latter half of the weekend.
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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Thursday
Mostly cloudy with scattered light rain and snow showers in the morning, becoming partly sunny in the afternoon with isolated showers limited to the southern Olympics.
Thursday
Night
Partly cloudy, to start, then clearing skies.
Thursday
Mostly cloudy with scattered light rain and snow showers in the morning, becoming partly sunny in the afternoon with isolated showers.
Thursday
Night
Partly cloudy, to start, then clearing skies.
Thursday
Mostly cloudy with isolated light rain and snow showers in the morning, becoming partly sunny in the afternoon.
Thursday
Night
Partly cloudy, to start, then clearing skies.
Thursday
Mostly cloudy with isolated light rain and snow showers in the morning, becoming partly sunny in the afternoon.
Thursday
Night
Partly cloudy, to start, then clearing skies.
Thursday
Mostly cloudy with an isolated sprinkle or flurry possible early, then becoming partly sunny in the afternoon. Light west winds at Pass level and ridgeline.
Thursday
Night
Partly cloudy, to start, then clearing skies. Light ridgeline and light or variable E winds at Pass level.
Thursday
Mostly cloudy with isolated light rain and snow showers in the morning, becoming partly sunny in the afternoon. Light west winds at Pass level and ridgeline.
Thursday
Night
Partly cloudy, to start, then clearing skies. Light ridgeline and light or variable E winds at Pass level.
Thursday
Partly cloudy.
Thursday
Night
Partly cloudy, to start, then clearing skies.
Thursday
Partly cloudy.
Thursday
Night
Partly cloudy, to start, then clearing skies.
Thursday
Partly cloudy.
Thursday
Night
Partly cloudy, to start, then clearing skies.
Thursday
Partly cloudy with a chance of a snow flurry or sprinkle early.
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).