A northward lifting warm front ends a multi-day atmospheric river event from south to north across Washington State on Wednesday. Heavy rain should taper off in the Paradise and Snoqualmie Pass areas by 10 AM; Stevens Pass area by noon; Mountain Loop area during the afternoon; and Mt. Baker area by the evening. Multiple days of mild WSW flow has raised snow levels across the region to 7500-8500 ft. The only holdouts will be deep, wind-sheltered valleys in the northeastern Cascades such as the Methow Valley where some cold air remains pooled. Washington Pass has changed over to rain or freezing rain. Moderate to strong ridgeline winds should continue for the east slopes of the Cascades and in areas more exposed to an increasing southerly component to the winds such as Hurricane Ridge and Mt. Baker.
The region should experience a mostly cloudy, but relatively dry and very mild evening. The low pressure associated with Wednesday's warm front should approach the mouth of the Columbia River overnight spreading periods of light rain back into the region in the early morning hours. The associated trough should bring in cooler air particularly for the southern Washington Cascades and Mt. Hood on Thursday. Snow levels should also drop to 4000-5500 ft by the afternoon with up to 0.5" of snow water equivalent for Mt. Hood and Paradise by the end of the day.
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 to moderate rain tapering to showers in the afternoon. Strong ridgeline wind gusts possible.
Wednesday
Night
Increasing light rain. Strong ridgeline wind gusts possible after midnight.
Wednesday
Heavy rain. Moderate to strong ridgeline winds.
Wednesday
Night
Light rain showers more likely after midnight. Strong wind gusts possible.
Wednesday
Heavy rain decreasing tapering from south to north in the afternoon.
Wednesday
Night
Periods of light rain possible after midnight.
Wednesday
Moderate rain at Paradise and light rain at White Pass and Crystal; mainly before 10 AM.
Wednesday
Night
Periods of light rain possible after midnight.
Wednesday
Heavy rain tapering off in the afternoon. Light W wind switching E at pass by late morning.
Wednesday
Night
Cloudy with periods of light rain possible after midnight. Light E wind at the Pass.
Wednesday
Heavy rain early in the day tapering quickly and ending around 10 AM. Light W wind switching E at pass by late morning.
Wednesday
Night
Cloudy with light rain possible after midnight. Light E wind at the Pass.
Wednesday
Light rain or freezing rain. Strong ridgeline wind gusts likely in the afternoon.
Wednesday
Night
Very light rain possible at times.
Wednesday
Moderate rain in the morning western part, with light rain or freezing rain further east. Mostly cloudy during the afternoon. Decreasing moderate to strong ridgeline winds.
Wednesday
Night
Mostly cloudy with light rain possible after midnight.
Wednesday
Light rain ending early, then becoming mostly cloudy. Strong ridgeline wind gusts possible in the morning.
Wednesday
Night
Mostly cloudy with periods of light rain possible after midnight.
Wednesday
Partly to mostly cloudy. Strong ridgeline wind gusts at times.
Wednesday
Night
Mostly cloudy with periods of light rain possible after midnight.
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).