A cold, unstable weather pattern remains across the Pacific Northwest, and snowfall will continue to accumulate. The trough axis will continue to dig southward in our offshore waters through the weekend, spinning weak disturbances and instability showers into our region. Models indicate a subtle warming trend through Saturday evening as WSW winds gradually switch more SWerly, bringing in milder air. This will raise snow levels from 1500-2500 ft on Saturday to 2000-3000 ft on Sunday. However, light pass-level winds should switch easterly Saturday night through Sunday, keeping the passes chilly.
In this pattern, it is difficult to determine precisely where heavier snow showers will focus in time and space. Models indicate a relatively even distribution of shower activity for the west slopes and passes Saturday morning. The focus of the precipitation gradually shifts northward and diminishes in the southern Cascades. By late Saturday night, Mt Hood will be mostly dry. Some heavier shower activity could move into the Olympics and Mt Baker areas Sunday afternoon as a more organized system approaches the region. Snow shower activity should be mostly light in the central and southern Cascades, but will be enhanced for Mt Rainier and Mt St Helens.
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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Saturday
Moderate snow showers. Light to moderate ridgeline winds.
Saturday
Night
Moderate snow showers.
Saturday
Increasing moderate to heavy snow showers. Increasing light to moderate ridgeline winds.
Saturday
Night
Moderate to occasionally heavy snow showers. Moderate ridgeline winds.
Saturday
Increasing moderate to heavy snow showers. Increasing light to moderate ridgeline winds.
Saturday
Night
Moderate to locally heavy snow showers.
Saturday
Moderate to heavy snow showers at Paradise; light to moderate at Crystal and White Pass. Moderate ridgeline winds.
Saturday
Night
Decreasing light to moderate snow showers.
Saturday
Increasing moderate snow showers. Light to moderate ridgeline and light W wind at the Pass.
Saturday
Night
Decreasing light to moderate snow showers. Light ridgeline and E wind at the Pass.
Saturday
Moderate to heavy snow showers. Decreasing light to moderate ridgeline and W wind at the Pass.
Saturday
Night
Decreasing light to moderate snow showers. Light ridgeline and E wind at the Pass.
Saturday
Increasing light to moderate snow showers. Light to moderate ridgeline winds.
Saturday
Night
Decreasing mostly light snow showers.
Saturday
Increasing light to moderate snow showers. Decreasing moderate ridgeline winds.
Saturday
Night
Decreasing mostly light snow showers.
Saturday
Decreasing light to moderate snow showers. Decreasing light to moderate ridgeline winds.
Saturday
Night
A few light snow showers decreasing or ending.
Saturday
Decreasing light to moderate snow showers. Moderate ridgeline winds.
Saturday
Night
Cloudy with a slight chance of snow showers. Light to 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).