Lingering showers associated with our departed atmospheric river should end early Saturday morning across northern Washington. A low spinning off the coast of Oregon lifts a band of light rain and snow into Mt Hood starting early Saturday with precipitation spreading into the southern Washington Cascades and Olympics as the day progresses. SE winds ramp up and may be strong at times through the mountain gaps of the southern Cascades. Snow levels should remain relatively steady around 4500-5000 ft.
Saturday night, the weakening low drifts toward the mouth of the Columbia with moisture wrapping around the low focusing on the E slopes of the Cascades. Moderate ridgeline winds (strong at times through the mountain gaps) should gradually ease. Snow levels should drop toward 4000-4500 ft as the trough brings in cooler air.
On Sunday, the low drifts northward toward the Olympic Mountains. As it does, winds shift from SE to SW as the day progresses. Expect increasing light to moderate rain/snow showers to the south of the low pressure in association with the wind shift. Expect slightly cooler temperatures with 3500-4000 ft snow levels, but still warmer than average temperatures for January.
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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Saturday
Light rain and snow showers primarily targeting the southern Olympics in the morning with some spillover to Hurricane Ridge. Light rain and snow focus on the SE Olympics in the afternoon while Hurricane Ridge likely dries out.
Saturday
Night
Light rain and snow continue in the SE Olympics while Hurricane Ridge remains mostly dry.
Saturday
Light rain and snow ending early, then becoming partly to mostly cloudy.
Saturday
Night
Cloudy with a chance of light rain or snow by morning.
Saturday
A few showers ending early, then partly to mostly cloudy.
Saturday
Night
Cloudy with a chance of light rain or snow by morning.
Saturday
Light rain and snow at times, heaviest southern volcanoes. Strong ridgeline winds possible near the Cascade Crest in the afternoon.
Saturday
Night
Light rain and snow at times. Strong ridgeline winds possible near the Cascade Crest in the evening.
Saturday
Showers ending early, then becoming mostly cloudy. Increasing light to moderate ridgeline and E wind at the Pass.
Saturday
Night
Mostly dry in the evening, with light rain and snow developing overnight. Moderate ridgeline and light to moderate E winds decreasing.
Saturday
Showers ending early, then becoming mostly cloudy. Increasing light to moderate ridgeline and E wind at the Pass.
Saturday
Night
Mostly dry in the evening, with light rain and snow developing overnight. Moderate ridgeline and light to moderate E winds decreasing.
Saturday
A few rain or snow showers early, then becoming mostly cloudy.
Saturday
Night
Increasing light rain and snow.
Saturday
Mostly cloudy.
Saturday
Night
Increasing light rain and snow.
Saturday
Increasing light rain and snow.
Saturday
Night
Increasing light to occasionally moderate rain and snow.
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).