A weak frontal system is slowly pushing through the forecast area this morning. The system will lift NE through mid-day, delivering modest amounts of snow and rain to the northwest Cascades and much lighter totals elsewhere. A quick 4-6" of snow above 3500' is likely in the Mt Baker area along with a period of moderate to strong ridgeline southerly winds. Areas east of the crest and south of I-90 and the Mt Hood area may see almost nothing. Cool easterly flow has kept snow levels around 3000' in the Cascade Passes. As milder air in SW flow pushes in this afternoon, we should see a bump in freezing levels for the Cascade Passes and along the east slopes of the Cascades. Before the precipitation tapers off mid-day, there may be a strange brew of wintry precipitation including freezing rain in places where low-level cold air and moisture and light precipitation line up.
While conditions dry out in most areas tonight, light warm frontal moisture from a system located well offshore will clip the Olympic mountains and perhaps the northwest Cascades overnight through Friday morning. An upper-level ridge centered over the Intermountain West will amplify on Friday and quickly shunt the precipitation well north into central British Columbia. We'll see another battle of cool easterly flow and multiple freezing levels with warmer air aloft riding in from the SW Thursday night and Friday. Freezing levels will be tricky as you approach the Cascade crest and along the east slopes of the Cascades in this nuanced setup. Areas west of the Cascade crest will see mid-mountain temperatures rise well into the 40s. We can expect filtered sunshine with passing high clouds on Friday as well.
Weather Forecast
Olympics
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West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
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Thursday
Light rain and snow this morning, then partly to mostly cloudy this afternoon.
Thursday
Night
Cloudy with periods of light rain or snow.
Thursday
Light to moderate rain and snow through mid-day, then scattered light rain and snow showers in the afternoon. Moderate to strong ridgeline winds tapering down this afternoon.
Thursday
Night
Cloudy with periods of light rain or snow.
Thursday
Light to occasionally moderate rain and snow this morning, then mostly cloudy with a chance of light rain or snow showers this afternoon.
Thursday
Night
Cloudy with a chance of light rain or snow.
Thursday
Periods of light rain and snow this morning, then mostly cloudy this afternoon. Moderate ridgeline winds.
Thursday
Night
Mostly cloudy. Cooler near White Pass with areas of low clouds.
Thursday
Light rain and snow through mid-day, becoming mostly cloudy this afternoon. Chance of light mixed precipitation late morning. Light Pass level and ridgeline winds becoming occasionally moderate this afternoon.
Thursday
Night
Mostly cloudy. Areas of low clouds near and east of the Pass. Light E winds at Pass level.
Thursday
Light rain and snow through mid-day, becoming mostly cloudy this afternoon. Chance of light mixed precipitation late morning. Moderate Pass level and ridgeline winds.
Thursday
Night
Mostly cloudy. Areas of low clouds near and east of the Pass. Light to moderate E winds at Pass level.
Thursday
Light rain and snow this morning, then partly to mostly sunny this afternoon.
Thursday
Night
Mostly cloudy. Areas of low clouds lower slopes and valleys.
Thursday
Periods of light rain and snow this morning mainly near the Cascade crest, then partly to mostly sunny this afternoon. Moderate ridgeline winds.
Thursday
Night
Mostly cloudy. Areas of low clouds lower slopes and valleys.
Thursday
Chance of light rain and snow this morning mainly near the Cascade crest, then partly to mostly sunny this afternoon. Periods of moderate ridgeline winds.
Thursday
Night
Mostly cloudy. Areas of low clouds lower slopes and valleys.
Thursday
Chance of light rain and snow this morning, then partly to mostly sunny this afternoon. Moderate to strong ridgeline winds tapering down this 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).