Another day, another atmospheric river, or at least that's how it feels at the start of this winter season. Heavy rain and high elevation snow will continue today, heaviest through mid-day, and become relatively lighter in the afternoon. Snow levels are high 9000', except in the East North/Washington Pass area where they are likely around 6500-7000', but will rise to 7500' later today. Besides precipitation, the winds will be the story with strong to extreme SW then WSW winds in all zones. Those strong winds will continue longest along the east slopes of the Cascades tonight, especially in the afternoon and evening, battering areas with downslope winds that have already have saturated soils and several rounds of strong gusty downslope winds.
Precipitation will taper down tonight along with a cooling trend. An area of convergence will bring some fresh snowfall above 4000-4500' to all areas, with a likely bullseye of 6-10" for the Cascades of Skagit and Whatcom counties where a convergence zone sets up this evening.
We'll see another pulse of moisture in our atmospheric river train on Tuesday that will target the west slopes of the Cascades from Snoqualmie Pass and norhtward with 1-1.5 inches of water. Snow levels will rise, so we'll see a transition back to rain for most trailheads and ski area bases, with cooler snow levels closer to the Canadian border. Winds won't be quite as extreme on Tuesday but will remain strong out of the west.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
Use dropdown to select your zone
Monday
Moderate to heavy rain and high elevation snow becoming lighter in the afternoon. Extreme winds.
Monday
Night
Mostly cloudy with light rain and snow showers. Strong ridgeline winds.
Monday
Heavy rain and high elevation snow becoming lighter in the afternoon. Extreme winds.
Monday
Night
Light to occasionally moderate rain and snow showers. Strong ridgeline winds.
Monday
Heavy rain and high elevation snow becoming lighter in the afternoon. Extreme winds.
Monday
Night
Light to moderate rain and snow showers. Moderate to strong ridgeline winds.
Monday
Heavy rain and high elevation snow becoming lighter in the afternoon. Extreme winds.
Monday
Night
Light to occasionally moderate rain and snow showers. Strong ridgeline winds.
Monday
Heavy rain and high elevation snow becoming lighter in the afternoon. Light E winds at Pass level becoming strong W in the afternoon. Strong to extreme SW winds at ridgeline.
Monday
Night
Light to occasionally moderate rain and snow showers. Strong WSW Pass level and ridgeline winds.
Monday
Heavy rain and high elevation snow becoming lighter in the afternoon. Moderate E winds at Pass level becoming strong W in the afternoon. Strong to extreme SW winds at ridgeline.
Monday
Night
Light to occasionally moderate rain and snow showers. Strong WSW Pass level and ridgeline winds.
Monday
Moderate rain and high elevation snow, heaviest near the crest. Strong to extreme winds.
Monday
Night
Light to occasionally moderate rain and snow showers heaviest near the crest. Strong ridgeline winds.
Monday
Moderate rain and high elevation snow, heaviest near the crest. Precipitation becoming lighter in the afternoon. Extreme winds.
Monday
Night
Light to occasionally moderate rain and snow showers, heaviest near the crest. Strong to extreme ridgeline winds.
Monday
Moderate rain and high elevation snow, heaviest near the crest. Precipitation becoming lighter in the afternoon. Extreme winds.
Monday
Night
Light to occasionally moderate rain and snow showers, heaviest near the crest. Strong to extreme ridgeline winds.
Monday
Moderate to occasionally heavy rain and high elevation snow becoming lighter in the afternoon. Extreme winds.
Monday
Night
Light to occasionally moderate rain and snow showers. Strong to extreme 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).