A warm front will slowly edge north today, spreading light snow into the central and north Cascades. The heaviest snowfall will hold off until tonight, with the higher snowfall totals centered on the south WA Cascades and Mt Hood area. Offshore flow and SE ridgeline winds will also ramp up today, peaking this evening. Cold air is currently being drawn across the Cascades, so look for falling temperatures in the western portion of West South like Paradise, and at Mt Hood as well.
SW winds aloft will pump milder in aloft over the next 36 hours and battle with the lower level easterly flow. We'll have a chance for a wintry mix including freezing rain first at Mt Hood later today and tonight, the White Pass area and other areas in West South later tonight, and the Snoqualmie Pass area sometime Friday morning. As the warm front lifts north on Friday, areas west of the Cascade crest like the Mt Baker area should see the snowline move uphill during the day. The coldest air north of I-90 near and along the east slopes of the Cascades should keep precipitation all in the form of snow through Friday afternoon. Freezing levels will begin to "pop" for southern areas and the Olympics on Friday as warmer air starts to win out.
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
Periods of light to occasionally moderate snow.
Thursday
Night
Periods of light to moderate rain and snow. Moderate to strong ridgeline winds.
Thursday
Cloudy. Light snow developing this afternoon. Moderate ridgeline winds.
Thursday
Night
Light to occasionally moderate snow. Moderate ridgeline winds.
Thursday
Periods of light snow. Moderate ridgeline winds.
Thursday
Night
Light to occasionally moderate snow. Moderate ridgeline winds.
Thursday
Light to occasionally moderate snow. Moderate to locally strong ridgeline winds. Falling temperatures western part of the zone during the day.
Thursday
Night
Light to moderate snow. Chance of freezing rain late White Pass area. Strong ridgeline winds.
Thursday
Periods of light snow this morning, occasionally moderate in the afternoon. Moderate E-SE ridgeline and Pass level winds.
Thursday
Night
Light to moderate snow. Moderate to strong E-SE ridgeline and Pass level winds.
Thursday
Periods of light snow this morning, occasionally moderate in the afternoon. Moderate to strong E-SE ridgeline and Pass level winds.
Thursday
Night
Light to moderate snow. Moderate to strong E-SE ridgeline and Pass level winds.
Thursday
Cloudy with periods of light snow, mainly in the afternoon. Moderate ridgeline winds.
Thursday
Night
Light snow. Moderate ridgeline winds.
Thursday
Cloudy with periods of light snow, becoming occasionally moderate in the afternoon. Moderate ridgeline winds.
Thursday
Night
Light to moderate snow. Moderate to strong E-SE ridgeline winds.
Thursday
Cloudy with periods of light snow, becoming occasionally moderate in the afternoon. Moderate ridgeline winds.
Thursday
Night
Light to moderate snow. Moderate to strong E-SE ridgeline winds.
Thursday
Moderate to occasionally heavy snow. Temperatures falling during the day. Moderate to strong ridgeline winds.
Thursday
Night
Light to moderate rain and snow. Chance of freezing rain. Moderate ridgeline winds.
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).