At 7-8 AM this morning a cold front crossing the Cascades puts an end to the Tuesday through Tuesday night atmospheric river event. This heavy rain, high-elevation snow, and freezing rain in cold valleys east of the Cascade Crest should rapidly drop off or end after 8 AM for most areas. It also comes with strong SSW winds shifting W, creating a convergence band dropping south toward Stevens Pass. The remnants of this convergence could keep more sustained light to moderate rain and snow going in the Stevens Pass area and southern Mountain Loop even as mostly light snow showers rapidly decrease elsewhere across the west slopes of the Cascades through the morning hours. Expect Moderate to strong W ridgeline winds to continue mostly near mountain gaps, the Cascade Crest, and east slopes of the Cascades. But these winds should gradually ease as the day progresses.
A broad ridge of high pressure brings rising freezing levels and increased temperatures overnight for Mt Hood and the Olympics.
The ridge amplifies on Thursday, but a stubby warm front should bring some mostly light precipitation along with S winds for the Olympics and Mt Baker areas. Low-level E winds will bring modestly cooler air through the mountain gaps, with temperatures hovering in the low to mid 30s.
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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Wednesday
Light rain and snow showers taper or end early, then mostly cloudy skies.
Wednesday
Night
Mostly cloudy with a slight chance of rain in the early morning hours.
Wednesday
Light rain and snow showers tapering as the day progresses. Decreasing moderate ridgeline winds with strong gusts.
Wednesday
Night
Mostly cloudy.
Wednesday
Heavy rain and snow quickly tapers to light rain and snow showers as temperatures cool. Convergence lingers in the southern part through mid-day. Decreasing moderate to strong ridgeline winds early, then decreasing.
Wednesday
Night
Mostly cloudy.
Wednesday
Moderate to heavy rain and snow quickly taper to light rain and snow showers as snow levels lower. Rapidly decreasing moderate to strong ridgeline winds.
Wednesday
Night
Mostly cloudy with a slight chance of rain in the early morning hours.
Wednesday
Moderate to heavy rain changing to light rain and snow showers with embedded moderate convergence through the morning hours. Lowering snow levels. Decreasing moderate ridgeline and light W wind at the Pass.
Wednesday
Night
Mostly cloudy. Light ridgeline and increasing E wind at the Pass.
Wednesday
Moderate to heavy rain changing to light rain and snow showers the morning hours. Lowering snow levels. Decreasing moderate to strong ridgeline and moderate W wind at the Pass.
Wednesday
Night
Mostly cloudy. Light ridgeline and increasing E wind at the Pass.
Wednesday
Heavy rain and snow tapers to light rain and snow showers from mid-morning onwards. Sun breaks increase during the afternoon. Moderate to strong ridgeline winds.
Wednesday
Night
Partly cloudy.
Wednesday
Heavy rain and high-elevation snow will give way to light rain and snow showers near the Cascade Crest from mid-morning onwards. Sun breaks will increase during the afternoon. Moderate to strong ridgeline winds.
Wednesday
Night
Partly cloudy.
Wednesday
Moderate rain and high-elevation snow will give way to light rain and snow showers near the Cascade Crest from mid-morning onwards. Sun breaks will increase during the afternoon. Decreasing moderate to strong ridgeline winds.
Wednesday
Night
Partly cloudy. Inversions possible.
Wednesday
Very heavy rain and snow tapering to light rain and snow showers by around 7 AM and largely ends by the afternoon. Strong ridgeline winds tapers to the moderate range by late morning.
Wednesday
Night
Increasing clouds with a slight chance of drizzle overnight. 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).