SSW flow continues to bring moisture into the Pacific Northwest ahead of a cold front slowly approaching the coastline. An initial N-S oriented rain band should exit the Cascades by 7 or 8 AM. Some areas will experience a relative break embedded in the frontal boundary, bringing steadier precipitation from SSW to NNE from the mid-morning through afternoon hours. Most areas will receive light rain and snow, but the volcanoes and other areas favored by the flow direction should expect moderate amounts. Snow levels should rise within the 3000-4000 ft range, peaking in the early afternoon and may be slightly lower E of the Cascade Crest with light upslope E flow.
A more substantial frontal wave currently off the California coast tracks toward the region overnight, bringing another period of moderate precipitation into the region. This feature tracks east of the Cascades, maintaining SE flow ahead of it, but flow switches W in its wake during the early morning hours as snow levels drop below Snoqualmie Pass. In the Mt Hood area, ridgeline winds will be strong through mid-morning Wednesday, tapering slightly in the afternoon. On Thursday, light to moderate and increasingly convective shower activity continues with drastically lower snow levels (1000-2000 ft). Thunderstorms remain possible in the afternoon, particularly in southern portions of the forecast region. Locally heavy precipitation is likely in convergence bands focusing on the Mountain Loop or Mt Baker areas.
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
Periods of light rain and snow in the northern Olympics (moderate in southern and eastern Olympics).
Wednesday
Night
Light rain and snow showers.
Wednesday
Moderate rain and snow. Decreasing moderate ridgeline winds.
Wednesday
Night
Moderate rain and snow.
Wednesday
Light to moderate rain and snow.
Wednesday
Night
Moderate rain and snow.
Wednesday
Moderate rain and snow at Paradise and Crystal; mostly light at White Pass.
Wednesday
Night
Light to moderate rain and snow. Ridgeline winds increase into the moderate range in the early morning hours.
Wednesday
Periods of light rain and snow. Light ridgeline and E wind at the Pass.
Wednesday
Night
Moderate rain and snow. Mostly light ridgeline and E wind switches W at the Pass overnight.
Wednesday
Periods of light rain and snow (moderate intensity at times). Light to occasionally moderate ridgeline and E wind at the Pass.
Wednesday
Night
Moderate rain and snow. Mostly light ridgeline and E wind switches W at the Pass overnight.
Wednesday
Periods of light rain and snow.
Wednesday
Night
Light to moderate rain and snow increases overnight.
Wednesday
Periods of light rain and snow.
Wednesday
Night
Light to moderate rain and snow increases overnight.
Wednesday
Periods of light rain and snow.
Wednesday
Night
Light rain and snow.
Wednesday
Periods of light to occasionally moderate rain and snow become steadier in the afternoon. Decreasing moderate ridgeline winds.
Wednesday
Night
Light to moderate rain and snow. Light and variable ridgeline winds increase into the moderate to strong range in the early morning hours.
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).