Weak ridging brings significantly above normal temperatures to the region through the weekend. The ridging wedges into the Pacific Northwest thanks to a split flow pattern as a closed low spins off the California Coastline and and more zonal flow resides across Canada. The descending air under the ridge will bring continued warming at all levels of the atmosphere. Freezing levels range from 7,500-9,500 ft on Saturday with light winds across the region and some filtered sunshine replacing predominantly clear skies from south to north. Freezing levels rise to 9,000-10,500 ft Saturday night and Sunday morning, dropping slightly in the afternoon. Mt Hood could get a few rain/snow showers Saturday evening into the overnight hours with snow levels around 8000-9000 ft.
For most middle elevation locations west of the Cascades, Saturday should be the warmest day. Increasing onshore gradients as a trough eases southward on Sunday will create some cooling, but won't lower freezing levels much, initially. Increasing light to moderate W winds that will accelerate through the mountain gaps, particularly late in 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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Saturday
Very warm. Mostly sunny with a few wispy high clouds in the afternoon.
Saturday
Night
Mild. Mostly clear with a very thin high clouds at times.
Saturday
Very warm. Mostly sunny.
Saturday
Night
Mild. Mostly clear with a very thin high clouds at times.
Saturday
Very warm. Mostly sunny with some filtered sunshine at times from late morning onward.
Saturday
Night
Mild. Mostly clear with a very thin high clouds at times.
Saturday
Very warm. Mostly sunny to start from highway 12 northward, with filtered sunshine or partially obscured skies furhter south. High clouds spread northward and linger throughout the day.
Saturday
Night
Mild. High clouds gradually decreasing.
Saturday
Very warm. Mostly sunny through mid-morning with filtered sunshine possible in the afternoon. Light ridgeline and W wind at the Pass.
Saturday
Night
Mild. Clear with very thin high clouds possible. Increasing light ridgeline and W wind at the Pass.
Saturday
Very warm. Mostly sunny through mid-morning with filtered sunshine possible in the afternoon. Light ridgeline and W wind at the Pass.
Saturday
Night
Mild. Clear with very thin high clouds possible. Increasing light ridgeline and W wind at the Pass.
Saturday
Very warm. Shallow inversion dissipates by 11 AM. Mostly sunny with a few high clouds possible in the afternoon.
Saturday
Night
Mild. Very shallow inversion possible overnight. Clear with a few very thin high clouds.
Saturday
Very warm. Mostly sunny through mid-morning with filtered sunshine possible in the afternoon.
Saturday
Night
Mild. Clear with very thin high clouds possible.
Saturday
Very warm. Filtered sunshine or obscured skies.
Saturday
Night
Mostly sunny to start from highway 12 northward, with filtered sunshine or partially obscured skies furhter south. High clouds spread northward and linger throughout the day.
Saturday
Very warm. Mostly obscured skies or filtered sunshine. Clouds increase during the afternoon.
Saturday
Night
Mild. Cloudy in the evening with a few light rain and highest elevation snow showers are possible in the evening. Clouds begin to thin 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).