A vertically stacked upper low off our coast will drift northward today. Steadier light to occasionally moderate precipitation extends over much of the region Friday morning. This moisture generally arrives on a SSW flow. Precipitation should become more showery by the afternoon. Expect spillover onto the east slopes of the Cascades with some light low-level E flow through mid-morning. The volcanoes will receive the most moisture. Snow levels should gradually lower in the 3500-4500 ft range.
Rain and snow showers become scattered to isolated as the upper low morphs into a weak trough overnight. Snow levels lower to around 3000-3500 ft.
Scattered to isolated rain and snow showers continue but gradually decrease as the weak upper trough moves onshore on Saturday. Snow levels remain steady but expect a slight mid-day increase.
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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Friday
Decreasing light rain and snow showers.
Friday
Night
Light rain and snow showers.
Friday
Moderate rain and snow. Light to moderate ridgeline winds.
Friday
Night
Decreasing light to moderate rain and snow showers. Light to moderate ridgeline winds.
Friday
Light to moderate rain and snow become showery in the afternoon.
Friday
Night
Decreasing light to occasionally moderate rain and snow showers.
Friday
Light to moderate rain and snow become showery in the afternoon.
Friday
Night
Decreasing light rain and snow showers.
Friday
Light rain and snow becomes showery in the afternoon. Light ridgeline winds. Light E wind shifts W at the Pass by late morning.
Friday
Night
Decreasing light rain and snow showers. Mostly light ridgeline and light W wind at the pass.
Friday
Light rain and snow becomes showery in the afternoon. Light ridgeline winds. Light E wind shifts W at the Pass by late morning.
Friday
Night
Decreasing light rain and snow showers. Light to moderate ridgeline and light W wind at the pass.
Friday
Periods of light rain and snow become showery in the afternoon.
Friday
Night
Isolated light rain and snow showers.
Friday
Periods of mostly light rain and snow become showery in the afternoon.
Friday
Night
Isolated light rain and snow showers.
Friday
Periods of mostly light rain and snow become showery in the afternoon.
Friday
Night
Isolated light rain and snow showers.
Friday
Periods of mostly light rain and snow become showery in the afternoon. Moderate ridgeline winds.
Friday
Night
Decreasing light rain and snow showers. Decreasing moderate ridgeline winds may become light overnight.
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).