We're in for wet and windy ride over the next 48 hours with the wettest conditions for areas near the Cascade Crest and along the west slopes of the Cascades.
Several waves of moisture will ride over the area in NW flow aloft. Today's precipitation will be light to occasionally moderate, with wetter impulses arriving Sunday night and again on Monday. Unfortunately, this isn't our cool NW flow pattern. With a strong upper level ridge offshore, milder air will shove its way into the mix. Snow levels will gradually rise to 3500-5000' across the area late this afternoon and basically stay there through Monday afternoon. Snowfall accumulations will increase with elevation.
There will be a strong drying trend east of the Cascade crest in this pattern. Expect far less precipitation the further east one travels from the Cascade crest along with downsloping winds = warmer temperatures. In areas with very light precipitation, like the Mt Hood area, you may see periods of light freezing rain in the mix today and tonight as warmer air punches in aloft.
W-NW winds will be strong along ridgelines and extreme in the alpine today through Monday. Be prepared for whiteout conditions if you travel above treeline during this period. A rapid cooling trend with more snow will take place Monday night.
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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Sunday
Cloudy with periods of light rain and snow. Strong winds.
Sunday
Night
Cloudy with light rain and snow. Strong winds.
Sunday
Light rain and snow, becoming occasionally moderate in the afternoon. Moderate ridgeline winds.
Sunday
Night
Light to moderate rain and snow. Moderate to strong ridgeline winds.
Sunday
Light rain and snow, becoming light to moderate in the afternoon. Moderate ridgeline winds.
Sunday
Night
Moderate rain and snow. Moderate to strong ridgeline winds.
Sunday
Light rain and snow, becoming light to moderate in the afternoon, heaviest Paradise area. Moderate to strong ridgeline winds.
Sunday
Night
Light to moderate rain and snow, heaviest Paradise area. Strong ridgeline winds.
Sunday
Light rain and snow, becoming light to moderate in the afternoon. Moderate to strong ridgeline and Pass level W winds.
Sunday
Night
Moderate rain and snow. Strong ridgeline and Pass level W winds.
Sunday
Light rain and snow, becoming light to moderate in the afternoon. Moderate to strong ridgeline and Pass level W winds.
Sunday
Night
Moderate rain and snow. Strong ridgeline and Pass level W winds.
Sunday
Cloudy with light rain and snow, heaviest near the Cascade crest. Strong ridgeline winds.
Sunday
Night
Cloudy with light to moderate rain and snow, heaviest near the Cascade crest. Strong ridgeline winds.
Sunday
Cloudy with periods of light rain and snow, heaviest near the Cascade crest. Strong ridgeline winds.
Sunday
Night
Cloudy with light to occasionally moderate rain and snow, heaviest near the Cascade crest. Strong to extreme ridgeline winds.
Sunday
Cloudy with periods of light rain and snow, heaviest near the Cascade crest. Strong ridgeline winds.
Sunday
Night
Cloudy with light to occasionally moderate rain and snow, heaviest near the Cascade crest. Strong to extreme ridgeline winds.
Sunday
Mostly cloudy with periods of light rain and snow or light freezing rain. Strong to extreme ridgeline winds.
Sunday
Night
Cloudy with periods of light rain and snow or light freezing rain. 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).