A weakening low its associated trough lifts northward offshore today. The package should bring moderate to occasionally strong winds, some cooling west of the Cascade Crest, a return to W flow through the passes by late morning, and wrap-around moisture impacting W. Washington today. Radar and satellite imagery show continuous moderate to occasionally heavy precipitation impacting the Olympic peninsula as it wraps around the back of the low pressure. This should slide ENE, impacting the northern Cascades during the mid-day hours before decreasing late in the day. Elsewhere, expect light to moderate showers with a shift to more westerly winds helping to bring precipitation to the central Cascades passes while increasing down-slope winds along the east slopes of the Cascades.
A weak and dissipating trough should bring some light snow showers Saturday night before it fizzles.
Sunday, a weak offshore front will either remain just offshore and mainly impact the Olympics or it may spread a band of light snow across the region in the morning hours. By afternoon, high pressure moves in from the east, bringing drying and E flow re-developing. Temperatures should also begin to warm up during 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
Moderate rain and snow early, then decreasing showers.
Saturday
Night
Light rain and snow showers.
Saturday
Moderate to heavy rain and snow. Strong ridgeline winds early decreasing and becoming moderate.
Saturday
Night
Light rain and snow showers.
Saturday
Moderate rain and snow peaking in the middle of the day. Moderate to strong ridgeline winds.
Saturday
Night
Light rain and snow showers.
Saturday
Light to moderate rain and snow showers, heaviest at Paradise.
Saturday
Night
Light rain and snow showers.
Saturday
Light to occasionally moderate rain and snow showers. E winds switching W at pass level by mid-morning.
Saturday
Night
Light rain and snow showers.
Saturday
Light to occasionally moderate rain and snow showers. E winds switching W at pass level by mid-morning.
Saturday
Night
Light rain and snow showers.
Saturday
Periods of light to moderate snow peaking in the mid-day hours.
Saturday
Night
Light snow showers.
Saturday
Light rain and snow peaking in the mid-day hours.
Saturday
Night
Light rain and snow showers.
Saturday
Light rain and snow showers.
Saturday
Night
Very light rain and snow showers.
Saturday
Moderate rain and snow. Moderate to strong 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).