A weakening cold cutoff upper low continues to drift eastward into the near-shore waters off the Washington Coast. Moderate to locally heavy rain and snow showers rotating around the low should disproportionately impact the Olympics and Mt. Baker areas on Friday. Later Friday afternoon, convective shower activity will increase in other parts of the Cascades. Graupel, locally intense snowfall rates, and isolated lightning strikes may accompany these convective showers. Snow levels will start the day below 3000 ft, but diurnal warming may create a rain/snow mix at Snoqualmie Pass later in the day. Mt. Baker and Hurricane Ridge could pick up 6-8" of snow during the day.
The closed low reaches the coastline as an open trough Friday night. SW winds will focus snow shower activity on the Cascade volcanoes with 5-10" of snow expected overnight.
The Trough pushes east of the area on Saturday. A westerly surge of winds behind the trough should maintain snow shower activity with the heaviest snowfall for Mt. Hood. A puget sound convergence zone forming in the central Cascades may also drop significant snowfall between Snoqualmie and Stevens passes.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
Use dropdown to select your zone
Friday
Moderate to heavy rain and snow.
Friday
Night
Light to moderate snow showers.
Friday
Increasing moderate to heavy rain and snow showers.
Friday
Night
Heavy snow showers.
Friday
Increasing light rain and snow showers.
Friday
Night
Increasing moderate rain and snow showers.
Friday
Light to moderate rain and snow showers, heaviest at Paradise.
Friday
Night
Moderate to heavy rain and snow showers at Paradise; light at Crystal and White Pass.
Friday
Light rain and snow showers. Light E wind at the Pass.
Friday
Night
Increasing light snow showers. Variable wind at the Pass.
Friday
Increasing light rain and snow showers. Accumulating snows mostly above 3500 ft. Light E winds at the Pass.
Friday
Night
Increasing light rain and snow showers. Variable wind at the Pass.
Friday
Light rain and snow showers.
Friday
Night
Light rain and snow showers.
Friday
Light rain and snow showers. Strong wind gusts at times.
Friday
Night
Light rain and snow showers. Strong wind gusts at times.
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).