The cold temperatures will be the biggest impact of a relatively static weather pattern. NNW aloft keeps our region dry and under the influence of an offshore ridge. Meanwhile, modified arctic air continues to spill into the region from the interior of the continent. Low-level E gradients and weak Fraser outflow at times continues to allow some of this cold air to trickle into the Puget Sound lowlands.
Most mountain locales are off to a chilly start with temperatures in the teens and low 20s. Washington Pass takes the "frozen" cake with a temperature of 4F and a low-level inversion. Temperatures should moderate into the mid to upper 20s in most areas by the afternoon. Expect light and variable winds along with mostly sunny skies.
A disturbance moving in on NNW flow will bring some more widespread high clouds and an uptick in NW or W ridgeline winds. Weak E pressure gradients still favor weak E flow at Snoqualmie Pass. Low temperatures should be similar to Saturday morning but could be slightly colder east of the Cascade Crest on Sunday. Temperatures rebound once again Sunday afternoon on the west slopes of the Cascades, but less further east. Easterly gradients begin to increase late in the day.
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
Sunny with a cold start, then moderating in the afternoon. A few mid- or high clouds at times. A chance of low clouds and fog below 3000 ft.
Saturday
Night
Thin high clouds. A chance of low clouds and fog below 3000 ft.
Saturday
Sunny and cold. A few mid or high clouds at times.
Saturday
Night
Cold. Thin high clouds.
Saturday
Sunny and cold. A few mid or high clouds at times.
Saturday
Night
Cold. Thin high clouds.
Saturday
Sunny and cold. A few mid or high clouds at times.
Saturday
Night
Cold. Thin high clouds.
Saturday
Sunny and cold. A few mid or high clouds at times. Light ridgeline and E wind at the Pass.
Saturday
Night
Cold with a low-level inversion. Thin high clouds. Light ridgeline and variable or E wind at the Pass.
Saturday
Sunny and cold. A few mid or high clouds at times. Light ridgeline and E wind at the Pass.
Saturday
Night
Cold with a low-level inversion. Thin high clouds. Light ridgeline and variable or E wind at the Pass.
Saturday
A very cold start with low-level inversions mixing out by late morning. Mostly sunny with a few high clouds.
Saturday
Night
Thin high clouds. Cold. Inversions form once again.
Saturday
A very cold start with low-level inversions mixing out by late morning. Mostly sunny with a few high clouds.
Saturday
Night
Thin high clouds. Cold. Inversions form once again.
Saturday
A very cold start with low-level inversions mixing out by late morning. Mostly sunny with a few high clouds.
Saturday
Night
Thin high clouds. Cold. Inversions form once again.
Saturday
Chilly start with temperatures moderating in the afternoon. Thin high clouds at times.
Saturday
Night
Cold with a low-level inversion. Thin high clouds.
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).