Today will be the last full day of our "fog ridge" (fog relative to whether you are at elevation or in the lowlands or a valley) before the weather pattern starts to change. We'll see one more day 10,000-11,000' freezing levels, and mid-mountain temperatures should peak in the 40s and even low 50s under sunny skies. Strong temperature inversions will make for a stark difference over relatively short elevation changes, with many lower elevation sites in the teens or 20s this morning and they will once again barely warm during the day. The stratus and low cloud placement and depth (4000-4500') will largely be unchanged, with easterly flow continuing to pull low clouds up to and near the Cascade Passes. Snoqualmie will once again bear the brunt of shallow, cold, and cloudy conditions at Pass level while the higher White and Stevens Pass will likely stay in the sunshine with the low clouds banked up just to the east.
We'll see a frontal system weaken as it approaches the coastline tonight and largely wash out as it runs into the ridge on Thursday. We'll see an increase in mid and high level clouds after sunrise on Thursday for the Cascades, and maybe some light precipitation over the Olympics during the day. After a warm Friday with rain/high elevation snow brushing the Olympics and northwest Cascades, a stronger frontal system is on tap for Saturday with a turn to cooler, snowier 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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Wednesday
Mostly sunny. Areas of valley fog. Light winds.
Wednesday
Night
Mostly clear in the evening then increasing high clouds after midnight. Areas of valley fog. Light to occasionally moderate ridgeline winds.
Wednesday
Mostly sunny. Areas of valley fog. Light winds.
Wednesday
Night
Mostly clear. Areas of valley fog. Light to occasionally moderate ridgeline winds.
Wednesday
Mostly sunny. Areas of valley fog. Light winds.
Wednesday
Night
Mostly clear. Areas of valley fog. Light to occasionally moderate ridgeline winds.
Wednesday
Mostly sunny. Areas of valley fog, especially near and east of White Pass. Light to occasionally moderate ridgeline winds.
Wednesday
Night
Mostly clear. Areas of valley fog, especially near and east of White Pass. Light to occasionally moderate ridgeline winds.
Wednesday
Mostly sunny mid and upper slopes. Areas of fog and low clouds, near and especially east of the Pass. Light to moderate E winds at Pass level and S-WSW ridgeline winds.
Wednesday
Night
Mostly clear mid and upper slopes. Areas of fog and low clouds, near and especially east of the Pass. Light to moderate E winds at Pass level and WSW ridgeline winds.
Wednesday
Mostly sunny mid and upper slopes. Areas of fog and low clouds at Pass level and especially east of the Pass. Moderate to occasionally strong E winds at Pass level and light to occasionally moderate S-WSW ridgeline winds.
Wednesday
Night
Mostly clear mid and upper slopes. Areas of fog and low clouds at Pass level and especially east of the Pass. Moderate E winds at Pass level and light to occasionally moderate WSW ridgeline winds.
Wednesday
Mostly sunny mid and upper slopes. Cloudy, colder, with low clouds and fog lower slopes and valleys. Light winds.
Wednesday
Night
Mostly clear mid and upper slopes. Cloudy, colder, with low clouds and fog lower slopes and valleys. Light to occasionally moderate ridgeline winds.
Wednesday
Mostly sunny mid and upper slopes. Cloudy, colder, with low clouds and fog lower slopes and valleys. Light to occasionally moderate ridgeline winds.
Wednesday
Night
Mostly clear mid and upper slopes. Cloudy, colder, with low clouds and fog lower slopes and valleys. Light to occasionally moderate ridgeline winds.
Wednesday
Mostly sunny mid and upper slopes. Cloudy, colder, with low clouds and fog lower slopes and valleys. Light winds.
Wednesday
Night
Mostly clear mid and upper slopes. Cloudy, colder, with low clouds and fog lower slopes and valleys. Light to occasionally moderate ridgeline winds.
Wednesday
Mostly sunny. Areas of low clouds and valley fog, especially east side of the mountain.
Wednesday
Night
Mostly clear. Areas of low clouds and valley fog, especially east side of the mountain.
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).