The Pacific Northwest remains near the western edge of a broad trough centered over the plains of Southern Canada. This trough is touching off a few light snow showers in the Stevens Pass and southern West Central areas this morning. That should dissipate by 10 AM along with the associated band of cloud cover. Sunshine will linger for parts of northern Washington, but an approaching low and associated warm front will gradually push mid and high clouds northward. ESE winds are ramping up near the Cascade Crest as the low moves toward the mouth of the Columbia River. These winds will be in the moderate range for favored areas near and west of the Cascade Crest. Increasing snow develops in the late morning hours for Mt Hood, and pushes into southern Washington during the afternoon.
The surface low off the mouth of the Columbia merges with a lobe of the broad upper trough overnight. The light to moderate snow increases with locally heavy snowfall for the volcanoes. Expect significant accumulations in the East South Washington Cascades and Mission Ridge areas as moderate ESE winds also favor these areas. The low continues to drift toward the coastline Thursday morning, moving onshore during the afternoon. Moderate to heavy snowfall continues for the southern Washington Cascades, SE Olympics, and Mt Hood area, but tapers into the light to moderate range by the afternoon. Expect a decrease in snowfall rates heading northward from Mt Rainier and only very light snow reaching the northern Cascades.
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
A mix of clouds and sun in the morning, then high clouds lowering and thickening in the afternoon.
Wednesday
Night
Periods of increasing light snow (moderate to heavy at times in the SE Olympics).
Wednesday
A mix of clouds and sun.
Wednesday
Night
Cloudy with occasional light snow.
Wednesday
Cloudy to start with a few light snow showers, then becoming mostly cloudy. Increasing moderate ridgeline winds near the Cascade Crest.
Wednesday
Night
Cloudy with periods of light snow. Moderate ridgeline winds.
Wednesday
Early sunshine, then high clouds lowering and thickening with light snow developing in the afternoon. Increasing moderate ridgeline winds near the Cascade Crest.
Wednesday
Night
Moderate snow (heavy for Mt St Helens and Mt Adams). Moderate to locally strong ridgeline winds.
Wednesday
Cloudy to start with a few light snow showers, then becoming mostly cloudy. Increasing light to moderate ridgeline and light E wind at the Pass.
Wednesday
Night
Cloudy with increasing periods of light snow. Moderate ridgeline winds. Light to occasionally moderate E winds at the Pass.
Wednesday
Periods of clouds and sun in the morning, then becoming mostly cloudy. Increasing moderate ridgeline and light to moderate E wind at the Pass. Strong gusts W of the Pass.
Wednesday
Night
Cloudy with increasing periods of light snow. Moderate ridgeline and E wind at the Pass. Strong gusts W of the Pass.
Wednesday
Mostly cloudy with a chance of snow flurries.
Wednesday
Night
Cloudy with periods of light snow.
Wednesday
Mostly cloudy with periods of very light snow.
Wednesday
Night
Cloudy with increasing light snow (potentially moderate in the Wenatchee Mountains).
Wednesday
Mostly cloudy with light snow developing in the afternoon.
Wednesday
Night
Increasing moderate snow.
Wednesday
Light snow develops in the late morning and becomes moderate in the afternoon.
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).