Our atmospheric river is on its last legs today and at the risk of sounding like a broken record, waves of moisture will rotate up from south to north once again today. The heaviest precipitation will still be focused on the northwest Cascades and the southern slopes of the Olympics with more modest amounts elsewhere. Mild air has worked its way across the east slopes of the Cascades with just a little bit more work to do for far-flung places like the Methow Valley which has been holding onto the wet snow at 32F.
Precipitation will be heaviest this morning through mid-day and then we'll start to see the frontal band slide inland and a switch to more SW-erly winds at ridgeline level. Mt Hood has been mild over this period but largely missing the rain/wet snow party like areas further north, and should start to see an increase in showers in the afternoon.
Light to moderate showers will continue Friday night. On Saturday, the parent upper low starts to pull coast to the Oregon coast. For the north/central Cascades, we should see a rare dry period emerge in the afternoon. Unfortunately for Mt Hood and the southern Washington Cascades, it looks a new band of showers will rotate up from the low-pressure system in the afternoon.
Snow levels will gradually lower Friday night and Sunday but will still be above most trailheads for the first half of the weekend.
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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Friday
Stormy with moderate rain and snow, heaviest south slopes of the Olympics and strong winds, becoming light to moderate showers in the afternoon.
Friday
Night
Light to occasionally moderate rain and snow showers.
Friday
Stormy with moderate to heavy rain and snow and strong winds, becoming light to moderate showers late in the afternoon.
Friday
Night
Light to moderate rain and snow showers.
Friday
Stormy with moderate to heavy rain and snow and moderate to strong winds, becoming light to moderate showers late in the afternoon.
Friday
Night
Light to occasionally moderate rain and snow showers.
Friday
Moderate rain and snow and moderate to strong winds, becoming light to moderate showers late in the afternoon.
Friday
Night
Light to occasionally moderate rain and snow showers.
Friday
Periods of light rain and snow. Light to moderate E-SE ridgeline and Pass level winds.
Friday
Night
Light to occasionally moderate rain and snow showers. Light winds at Pass level.
Friday
Periods of light to occasionally moderate rain and snow. Light to moderate E-SE ridgeline and Pass level winds.
Friday
Night
Light to occasionally moderate rain and snow showers. Light winds at Pass level.
Friday
Light to occasionally moderate rain and snow becoming light showers late in the afternoon. Moderate ridgeline winds.
Friday
Night
Light rain and snow showers.
Friday
Light to occasionally moderate rain and snow becoming light showers late in the afternoon. Moderate to strong ridgeline winds.
Friday
Night
Light rain and snow showers.
Friday
Light to occasionally moderate rain and snow becoming light showers late in the afternoon. Moderate ridgeline winds.
Friday
Night
Light rain and snow showers.
Friday
Cloudy with periods of light rain or snow in the morning, then light to occasionally moderate rain and snow in the afternoon. Moderate to strong ridgeline winds easing in the afternoon.
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).