A broad, closed upper low extends from Vancouver Island to northern California. A shortwave trough rotating around the low will pass through the Cascades this morning, bringing a steadier band of N-S-oriented rain and snow to the Cascades as the day progresses. Rain and snow started during the early morning hours around Mt Hood and should spread to the east slopes of the Cascades during the morning hours eventually to most of the Cascades by the afternoon hours. Most of the precipitation should be light, but periods of moderate intensity are possible, particularly around the Wenatchee Mountains, East South Cascades, and Mt Hood. Winds should be light and out of the N or NE at upper elevations, while middle and lower elevations have an increasing westerly component. Snow levels will be on the cool side, hovering around 2000 ft in the morning and rising to around 3000 ft in the afternoon.
Precipitation tapers across the region Thursday night as the low center shifts south and slightly eastward. Through Friday, there should be enough instability to touch off isolated showers, particularly in the southern half of the forecast region. Expect more sunshine and freezing levels rising to 4500-5000 ft for the Olympics and Mt Baker areas, while areas further south get isolated snow showers down to around 2500-4000 ft.
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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Thursday
Mostly cloudy with some filtered sunshine at times and a few periods of light rain and snow.
Thursday
Night
Mostly cloudy with periods of light rain and snow.
Thursday
Cloudy with a few periods of light rain and snow, mainly during the afternoon hours.
Thursday
Night
Mostly cloudy with a few periods of light rain and snow decreasing overnight.
Thursday
Cloudy with a few periods of light rain and snow, mainly during the afternoon hours.
Thursday
Night
Mostly cloudy with a few periods of light rain and snow decreasing overnight.
Thursday
Cloudy with increasing periods of light to occasionally moderate rain and snow.
Thursday
Night
Mostly cloudy with decreasing periods of light rain and snow.
Thursday
Cloudy with increasing periods of light rain and snow, mainly during the afternoon hours. Light ridgeline and W wind at the Pass.
Thursday
Night
Mostly cloudy with a few periods of light rain and snow decreasing overnight. Light ridgeline and W wind at the Pass.
Thursday
Cloudy with increasing periods of light rain and snow, mainly during the afternoon hours. Light ridgeline and W wind at the Pass.
Thursday
Night
Mostly cloudy with a few periods of light rain and snow decreasing overnight. Light to moderate ridgeline and W wind at the Pass.
Thursday
Cloudy with a few periods of light rain and snow, mainly during the afternoon hours.
Thursday
Night
Mostly cloudy with a few periods of light rain and snow decreasing overnight.
Thursday
Cloudy with increasing periods of light to occasionally moderate rain and snow, mainly during the afternoon hours.
Thursday
Night
Mostly cloudy with periods of light rain and snow decreasing overnight.
Thursday
Cloudy with increasing periods of light to occasionally moderate rain and snow, mainly during the afternoon hours.
Thursday
Night
Mostly cloudy with periods of light rain and snow decreasing or ending overnight.
Thursday
Cloudy with increasing periods of light to occasionally moderate rain and snow, mainly during the afternoon hours.
Thursday
Night
Mostly cloudy with periods of light rain and snow decreasing overnight.
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).