An upper-level front moved through with 4-10" of snowfall overnight. The parent low sits and spins just north of Vancouver Island. In the wake of the front, moderate SW winds are bringing moisture-laden showers into the Cascades, focusing on Mt. Rainier northward. This pattern should continue for much of the day with the most significant snowfall around Mt. Baker where we expect another 6-12" of snow. Snow levels remain uncertain at Snoqualmie Pass where we expect the mid-level winds to eventually overwhelm the weak low-level E flow to result in a transition to rain at Pass level. A more significant atmospheric river aims toward northern California. The southern portions of the area could expect some light, but steady rain/snow during the afternoon and evening as the outer edge of this feature clips northern Oregon and southernmost Washington.
Mostly light shower activity wrapping around the stationary low should continue to taper overnight, but several high-resolution weather models don't show the water numbers ticking down as quickly. For now, we expect another 5-10" of snow overnight for Mt. Baker with lesser amounts further south along the Cascade Crest.
The stationary low finally moves onshore and dissipates as a high-pressure ridge builds offshore. Mostly very light snow shower activity could up to two inches of snowfall with mostly cloudy skies continuing for the west slopes of the Cascades. Temperatures should be near seasonable norms with snow levels back below all the major passes.
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
Light rain and snow showers.
Friday
Night
Decreasing very light rain/snow showers.
Friday
Moderate to heavy rain/snow.
Friday
Night
Moderate rain/snow showers and convergence.
Friday
Moderate rain and snow showers.
Friday
Night
Light to occasionally moderate snow showers and convergence.
Friday
Light to moderate snow showers, heaviest at Paradise. Gradually decreasing ridgeline winds may be strong early in the day at White Pass.
Friday
Night
Decreasing light rain/snow showers.
Friday
Moderate snow showers. Moderate ridgeline winds. Light E may or may not W winds at the Pass.
Friday
Night
Decreasing light rain/snow showers. Decreasing moderate ridgleline and light W wind at the Pass.
Friday
Moderate snow showers. Moderate ridgeline winds. Light E may or may not W winds at the Pass.
Friday
Night
Decreasing light rain/snow showers. Decreasing moderate ridgleline and light W wind at the Pass.
Friday
Light rain and snow showers.
Friday
Night
Decreasing light rain/snow showers.
Friday
Moderate rain and snow showers (western part); light rain and snow showers further east.
Friday
Night
Decreasing light rain/snow showers.
Friday
Light rain and snow showers with some steady light precipitation possible late in the day.
Friday
Night
A few sprinkles or flurries in the evening then mostly cloudy.
Friday
Light to occasionally moderate rain and snow showers may transition to steady precipitation late in the afternoon.
Friday
Night
Light rain/snow early quickly tapering to flurries.
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).