Forecast updated 0740 to fix an issue with the snow levels.
An upper-level and surface low-pressure system spins along the Washington Coastline on Thursday, bringing low-density snow to most of our region. An associated frontal band of moderate snowfall stalls over the central Washington Cascades and northern Olympics through the morning hours, but precipitation should gradually taper as the day progresses. South of the front, light to moderate snow showers continue for the southern Washington Cascades and Mt Hood area. The heaviest snowfall will be associated with SE winds in the SE Olympics, where we expect another 8-12" of snow. Other favored areas include the southern Cascade Volcanoes and Wenatchee Mountains where we expect 4-8" of snowfall today.
The remains of the upper low move east through the Cascades overnight, with shower activity ending quickly for the central and northern Washington Cascades. Mostly light snow or snow shower activity continues, particularly for Mt Hood as a stationary front stalls over the area.
On Friday, a weak ridge moves into the region, bringing a mostly dry day with some high clouds although Mt Hood can expect lingering light snow early in the day. ESE ridgeline and gap winds increase into the moderate range, with strong gusts expected in the afternoon. Temperatures stay cold east of the Cascades but expect a strong warming trend for areas not exposed to the cooling effects of the E flow.
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
Moderate snow becoming light in the afternoon at Hurricane Ridge. Heavy snow becomes moderate in the afternoon in the SE Olympics.
Thursday
Night
Light snow ending during the evening hours, then becoming partly cloudy.
Thursday
Cloudy with a chance of light snow (mainly in the Highway 20 corridor).
Thursday
Night
Partly cloudy early, then mostly clearing skies.
Thursday
Cloudy with periods of light snow. Decreasing moderate ridgeline winds.
Thursday
Night
Mostly cloudy with a chance of snow flurries in the evening. Mostly clear skies overnight with some high clouds.
Thursday
Decreasing moderate snow (heaviest on the volcanoes). Decreasing moderate ridgeline winds.
Thursday
Night
Decreasing light snow showers.
Thursday
Decreasing light snow. Decreasing light to moderate ridgeline and light E wind at the Pass.
Thursday
Night
Partly cloudy with a chance of snow flurries in the evening. Increasing light ridgeline and E wind at the Pass.
Thursday
Decreasing light snow. Decreasing moderate ridgeline and light to moderate E wind at the Pass.
Thursday
Night
Partly cloudy with a chance of snow flurries in the evening. Increasing light ridgeline and E wind at the Pass.
Thursday
Cloudy with light snow at times.
Thursday
Night
A chance of snow flurries in the evening. Clearing skies overnight.
Thursday
Decreasing light to moderate snow becomes showery.
Thursday
Night
A chance of snow flurries in the evening, then mostly clearing skies overnight.
Thursday
Decreasing light to occasionally moderate snow becomes showery.
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).