Flat upper level ridging offshore will allow high clouds to stream across Washington state today, thicker near the Canadian border. Combined with low level clouds west of the Cascade crest, partly to mostly cloudy conditions will stay in place for today with few clouds further south of Hwy 2 and east of the Cascade crest. Today will be mild across the region but freezing levels dramatically increase as you travel south of the Columbia River to around 10,000'.
A fast-moving frontal system will approach from the NW overnight. Precipitation will quickly become heavy over the northwest Cascades and moderate over the Olympics early tomorrow morning. Westerly winds will also ramp up quickly tomorrow across all areas with this sytem. By the end of the day, expect storm conditions to develop in most areas. While this system will start off on the mild side, the front should pass through the central Cascades around 3 pm with snow levels quickly dropping to 2000-3000' by late afternoon.
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
Partly to mostly cloudy. Periods of high overcast.
Saturday
Night
Cloudy with light rain and snow developing late. Increasing ridgeline winds.
Saturday
Mostly cloudy. Periods of high overcast.
Saturday
Night
Cloudy with light rain and snow developing late after midnight. Increasing ridgeline winds.
Saturday
Mostly cloudy. Periods of high clouds.
Saturday
Night
Cloudy with light rain and snow developing late. Increasing ridgeline winds.
Saturday
Mostly cloudy. Periods of high clouds. Light to moderate west winds at Pass level.
Saturday
Night
Partly cloudy in the evening becoming cloudy after midnight. Increasing ridgeline winds.
Saturday
Mostly cloudy. Periods of high clouds. Light to moderate west winds at Pass level.
Saturday
Night
Mostly cloudy in the evening becoming cloudy after midnight. Increasing ridgeline and Pass level winds.
Saturday
Partly to mostly cloudy. Periods of high clouds.
Saturday
Night
Mostly cloudy in the evening becoming cloudy after midnight. Increasing ridgeline and Pass level winds.
Saturday
Partly to mostly cloudy. Periods of high clouds.
Saturday
Night
Mostly cloudy in the evening becoming cloudy after midnight. Increasing ridgeline winds.
Saturday
Partly to mostly sunny. Periods of high clouds.
Saturday
Night
Partly cloudy in the evening becoming cloudy after midnight. Increasing ridgeline winds.
Saturday
Partly to mostly sunny. Periods of high clouds.
Saturday
Night
Partly cloudy in the evening becoming cloudy after midnight. Increasing ridgeline winds.
Saturday
Mostly sunny. Periods of high clouds.
Saturday
Night
Partly cloudy in the evening becoming cloudy late. Increasing ridgeline winds.
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).