A strong upper-level high pressure remains centered off the Oregon coast throughout the forecast period, bringing unseasonably warm air and low relative humidity. The Quillayute sounding reported an 11,300 ft freezing level early Saturday morning and the mercury climbed to 32F at Camp Muir. 10,000-12,000 ft freezing levels should continue through the weekend. Temperatures should rise into the mid-40s to lower 50s at most mountain stations below 7000 ft. Light NNW winds continue through Sunday morning.
An inversion early Saturday morning can be seen in temperatures below around 5000 ft. The major mountain passes in Washington State all have temperatures below freezing and are the only NWAC stations with sub-freezing temperatures. These inversions should all mix out by around 10 AM. Inversions will re-form Saturday night and should once again mix out by around 10 AM on Sunday.
High pressure exists at the surface as well. Very light low-level E flow should continue through Sunday morning. A very weak upper-level disturbance sliding down the coast from Canada should switch upper-level winds WNW and low-level winds W on Sunday afternoon. It will also dampen the ridge, to reduce freezing levels slightly. Nevertheless, most areas will see high temperatures in the mid-40s to lower 50s.
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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Saturday
Mostly sunny and unseasonably mild with a low-level inversion mixing out around 10 AM. Fog in low-elevation valleys.
Saturday
Night
Mostly sunny and unseasonably mild with a low-level inversion. Fog in low-elevation valleys.
Saturday
Mostly sunny and unseasonably mild with a low-level inversion mixing out around 10 AM. Fog in low-elevation valleys.
Saturday
Night
Mostly sunny and unseasonably mild with a low-level inversion. Fog in low-elevation valleys.
Saturday
Mostly sunny and unseasonably mild with a low-level inversion mixing out around 10 AM. Fog in low-elevation valleys.
Saturday
Night
Mostly sunny and unseasonably mild with a low-level inversion. Fog in low-elevation valleys.
Saturday
Mostly sunny and unseasonably mild with a low-level inversion mixing out around 10 AM. Fog in low-elevation valleys.
Saturday
Night
Mostly sunny and unseasonably mild with a low-level inversion. Fog in low-elevation valleys.
Saturday
Mostly sunny and unseasonably mild with a low-level inversion mixing out around 10 AM. Fog in low-elevation valleys. Increasing light E wind at the Pass.
Saturday
Night
Mostly sunny and unseasonably mild with a low-level inversion. Fog in low-elevation valleys. Light E flow switching W at the Pass.
Saturday
Mostly sunny and unseasonably mild with a low-level inversion mixing out around 10 AM. Fog in low-elevation valleys. Increasing light E wind at the Pass.
Saturday
Night
Mostly sunny and unseasonably mild with a low-level inversion. Fog in low-elevation valleys. Light E flow switching W at the Pass.
Saturday
Mostly sunny and unseasonably mild with a low-level inversion mixing out around 10 AM. Fog in low-elevation valleys.
Saturday
Night
Mostly sunny and unseasonably mild with a low-level inversion. Fog in low-elevation valleys.
Saturday
Mostly sunny and unseasonably mild with a low-level inversion mixing out around 10 AM. Fog in low-elevation valleys.
Saturday
Night
Mostly sunny and unseasonably mild with a low-level inversion. Fog in low-elevation valleys.
Saturday
Mostly sunny and unseasonably mild with a low-level inversion mixing out around 10 AM. Fog in low-elevation valleys.
Saturday
Night
Mostly sunny and unseasonably mild with a low-level inversion. Fog in low-elevation valleys.
Saturday
Mostly sunny and unseasonably mild with a low-level inversion mixing out around 10 AM. Fog in low-elevation valleys.
Saturday
Night
Mostly sunny and unseasonably mild with a low-level inversion. Fog in low-elevation valleys.
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).