A frontal passage early Tuesday morning has allowed much of the region to dry out from the Christmas atmospheric river. A few bands of SW-NE-oriented snowfall over the central Cascades and Mt Baker area should rapidly taper by 10 AM with up to an inch of additional snow accumulation expected. Snow levels lowered to around 3500-4000 ft for the west slopes of the Cascades with snow levels below 3000 ft for the mountain passes, thanks to light E flow.
A weak ridge moves over the region this afternoon, bringing partly cloudy skies during the mid-day hours before mid-level clouds increase late in the day.
Tuesday night, a stubby warm front brings a chance of very light rain and high-elevation snow to the Olympics from the late evening onwards. The chance of some light rain or snow extends to the west slopes of the Cascades overnight. Snoqualmie Pass could receive a wintry mix or snow. The main story will be increasing E flow becoming moderate to strong through the mountain gaps with locally very strong gusts west of the mountain gaps. These winds will impact most areas near the Cascade Crest from Washington Pass to Mt Hood.
A weakening cold front arrives Wednesday with bands of mostly light showers moving into the region on SSW flow. Once again, the pattern favors the Olympics, northern Cascades, and southern Cascade Volcanoes. Snow levels will be elevated (5000-7000 ft) west of the Cascade Crest, but expect periods of snowfall or wintry mix east of the Cascades and through the mountain gaps.
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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Tuesday
Partly cloudy in the morning, then mid-level clouds moving in during the afternoon. Light ridgeline winds.
Tuesday
Night
A chance of light rain or snow from late evening onwards. Moderate to strong ridgeline winds.
Tuesday
Convergence rain and snow tapers off before 10 AM, then mostly cloudy skies.
Tuesday
Night
Cloudy with light rain or snow in the early morning hours.
Tuesday
Convergence rain and snow tapers off before 10 AM, then mostly cloudy skies.
Tuesday
Night
Cloudy with light rain or snow in the early morning hours.
Tuesday
Partly to mostly cloudy in the morning, then becoming cloudy late in the day.
Tuesday
Night
Cloudy with a chance of light rain or snow in the early morning hours.
Tuesday
Light snow or flurries early, then becoming mostly cloudy. Light ridgeline and E wind at the Pass.
Tuesday
Night
Cloudy with a chance of light snow in the early morning hours. Increasing moderate ridgeline and E wind at the Pass.
Tuesday
Light snow or flurries early, then becoming mostly cloudy. Light to occasionally moderate ridgeline and E wind at the Pass.
Tuesday
Night
Cloudy with a chance of light mixed precipitation or snow in the early morning hours. Increasing moderate to strong ridgeline and E wind at the Pass. Winds may be locally very strong in the Cascade foothills west of the Pass.
Tuesday
A few snow flurries early, then becoming partly cloudy.
Tuesday
Night
Cloudy with a chance of light snow in the early morning hours.
Tuesday
Partly cloudy skies with increasing clouds late in the day.
Tuesday
Night
Cloudy with a chance of slight chance of light snow in the early morning hours.
Tuesday
Partly cloudy skies with increasing clouds late in the day.
Tuesday
Night
Mostly cloudy.
Tuesday
A few snow flurries early, then becoming partly cloudy during the mid-day hours. Clouds increase late in the day. Light to moderate ridgeline winds.
Tuesday
Night
Cloudy with a chance of light rain or snow in the early morning hours. 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).