Snow showers currently over the central-west and northwest Cascades will continue through this morning and spread further south and east as the day continues. Modified arctic air has been slow to spill out of the Fraser Valley and down the east side of the Cascades with a weak surface low hung up offshore further north. This progression should still happen today, dragging those light snow showers further south. Heavier snowfall rates are most likely in the areas where moister Pacific air overruns the very cold arctic air and in Convergence zone bands. Snow showers should fill in for both sides of the Cascades today as well. Moderate to locally strong westerly ridgeline winds can be found in most areas, with the strongest winds down at Mt. Hood. Places in the north will see a sharp cooling trend as the arctic air sloshes southwestward.
The showers should start to run out of juice overnight but not cease completely as much colder air filters into the region. Low level moisture and isolated/scattered snow showers will stick around on Monday with cold air entrenched on both sides of the Washington 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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Sunday
Light snow showers, becoming light to occasionally moderate in the afternoon. Moderate ridgeline winds in the afternoon. Temperatures dropping during the day and turning much colder.
Sunday
Night
Mostly cloudy with scattered light snow showers. Very cold.
Sunday
Light to moderate snow showers becoming scattered light snow showers in the afternoon. Temperatures dropping during the day and turning much colder.
Sunday
Night
Mostly cloudy with scattered light snow showers. Very cold.
Sunday
Light to moderate snow shower, occasionally heavy in convergence bands. Temperatures dropping during the day and turning much colder.
Sunday
Night
Light snow showers becoming mostly cloudy and scattered showers late in the evening.
Sunday
Mostly cloudy with light scattered snow showers in the morning. Showers becoming steadier in the afternoon. Ridgeline winds increasing and becoming moderate to strong in the afternoon.
Sunday
Night
Light snow showers becoming mostly cloudy and scattered showers after midnight. Moderate to strong ridgeline winds decreasing overnight.
Sunday
Light snow showers, becoming light to occasionally moderate mid-day or in the afternoon. Moderate to strong ridgeline and Pass level winds.
Sunday
Night
Light snow showers becoming mostly cloudy and scattered showers late in the evening. Moderate westerly Pass level and ridgeline winds decreasing overnight.
Sunday
Light snow showers, becoming light to occasionally moderate in the afternoon. Moderate to strong ridgeline and Pass level winds.
Sunday
Night
Light snow showers becoming mostly cloudy and scattered showers late in the evening. Moderate to strong westerly Pass level and ridgeline winds decreasing overnight.
Sunday
Cloudy with light snow showers.
Sunday
Night
Mostly cloudy with scattered light snow showers.Very cold.
Sunday
Cloudy with light snow showers, occasionally moderate near the Cascade crest in the afternoon. Moderate to strong ridgeline winds.
Sunday
Night
Cloudy with light snow showers in the evening, then mostly cloudy with scattered light snow showers overnight. Moderate to strong ridgeline winds decreasing overnight.
Sunday
Mostly cloudy with scattered snow showers, becoming steadier in the afternoon.
Sunday
Night
Cloudy with light snow showers, occasionally moderate near the Cascade crest in the evening.
Sunday
Partly to mostly cloudy with light snow showers in the afternoon. Strong to extreme 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).