We're entering a very wet, atmospheric river type pattern with warm air streaming in on SW flow.
A front crossing western Washington with a band of precipitation weakens as it displaces the high pressure and moves into the Cascades from mid-morning onward. Significantly warmer temperatures are in place west of the Cascade Crest than further east. Paradise sits at 36F while Snoqualmie Pass remains in the lower 20s. E flow throughout the forecast period should maintain cool conditions through the mountain gaps. As precipitation moves into the Cascades, expect rain and high elevation snow west of the Cascade Crest with a rain/freezing rain mix through the passes and further east. Precipitation should be generally light, with freezing rain likely to have the greatest impact where it occurs.
The initial front moves out of the picture, giving the region a mostly dry evening. However, a stronger and wetter system tracks a low toward northern Vancouver Island and begins to impact Washington State Monday night with increasing SW winds and moderate rain and snow, particularly across the NW parts of the state.
A third wave of moisture arrives with another shortwave feature arriving ramping up rain, high elevation snow, and winds throughout the day on Tuesday. The location of the heaviest rain and snow remains uncertain, but will likely be in the central or northern Washington Cascades and Olympics.
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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Monday
Decreasing light rain and snow. Strong ridgeline wind gusts possible in the morning.
Monday
Night
Increasing light rain and snow.
Monday
Increasing light rain and snow.
Monday
Night
Light rain and snow becoming moderate to occasionally heavy overnight.
Monday
Increasing light rain and snow.
Monday
Night
Light rain and snow becoming moderate overnight.
Monday
Increasing light rain and snow.
Monday
Night
Mostly dry in the evening with increasing light rain and snow overnight (possibly moderate at Paradise).
Monday
Light snow with lower elevation freezing rain developing during the mid-morning through afternoon hours. Light E winds at the Pass.
Monday
Night
Increasing light rain or freezing rain. Increasing light E winds at the Pass.
Monday
Light snow with lower elevation freezing rain or rain developing during the mid-morning through afternoon hours. Light to moderate E winds at the Pass.
Monday
Night
Increasing light rain or freezing rain. Increasing light E winds at the Pass.
Monday
Light snow developing from late morning onwards.
Monday
Night
Increasing light snow.
Monday
Light snow or freezing rain from late morning onwards.
Monday
Night
Increasing very light snow or freezing rain.
Monday
Light snow or freezing rain from late morning onwards.
Monday
Night
A mostly dry evening with light snow or freezing rain overnight.
Monday
Increasing light rain or snow with some freezing fog possible.
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).