An upper level trough will pass through southern Washington and Oregon today, bringing locally moderate showers and strong to even extreme winds to the Mt Hood area and the far southern Washington Cascades. Further north, we can expect a few scattered showers this morning, mostly near and west of the Cascade crest giving way to a mix of sun and clouds late morning through early afternoon. Weak upper level ridging will shift closer to the coastline in the afternoon, and help trap low level moisture, likely leading to an increase in clouds in the afternoon. More sun and slightly higher freezing levels can be found east of the Cascade crest.
Weak warm frontal moisture will work its way over the area Sunday night with a frontal boundary sagging south over the area on Monday. Southerly winds will crank up again for places like Hurricane Ridge, Mt Baker and Crystal Mt overnight. This event has been deemed a weak "atmospheric river" and indeed precipitation totals through early Tuesday morning seem much lighter than some of the more impactful events we've seen this winter. Snow levels will also not be as high with this event, likely peaking in the 4000-5000' (higher at Mt Hood), Monday/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
Partly to mostly sunny. Increasing clouds late.
Sunday
Night
Cloudy with light rain and snow developing. Ridgeline winds becoming strong.
Sunday
Mostly cloudy with a chance of showers in the morning, then partly sunny late morning, then increasing clouds late. Moderate ridgeline winds easing in the afternoon.
Sunday
Night
Cloudy with light to occasionally moderate rain and snow developing overnight. Ridgeline winds becoming strong.
Sunday
Mostly cloudy with a chance of showers in the morning, then partly sunny late morning, then increasing clouds late. Moderate ridgeline winds easing in the afternoon.
Sunday
Night
Cloudy with light to occasionally moderate rain and snow developing overnight. Ridgeline winds becoming strong.
Sunday
Cloudy with light to moderate showers mainly in the morning. Strong to moderate ridgeline winds easing in the afternoon.
Sunday
Night
Cloudy with light rain and snow developing overnight. Ridgeline winds becoming strong.
Sunday
Mostly cloudy with a chance of showers in the morning, then partly sunny late morning, then increasing clouds late. Light west winds at Pass level.
Sunday
Night
Cloudy with light rain and snow developing overnight. Light east winds at Pass level.
Sunday
Mostly cloudy with a chance of showers in the morning, then partly sunny late morning, then increasing clouds late. Light west winds at Pass level.
Sunday
Night
Cloudy with light to occasionally moderate rain and snow developing overnight. Light east winds at Pass level.
Sunday
Mostly cloudy with a slight chance of showers in the morning near the Cascade crest, then partly to mostly sunny late morning, then increasing clouds late.
Sunday
Night
Cloudy with light to occasionally moderate rain and snow developing overnight. Light east winds at Pass level.
Sunday
Mostly cloudy with a slight chance of showers in the morning near the Cascade crest, then partly to mostly sunny late morning, then increasing clouds late.
Sunday
Night
Cloudy with light to occasionally moderate rain and snow developing overnight.
Sunday
Mostly cloudy with a slight chance of showers in the morning near the Cascade crest, then partly to mostly sunny late morning, then increasing clouds late.
Sunday
Night
Cloudy with light to occasionally moderate rain and snow developing overnight.
Sunday
Moderate rain and snow showers in the morning, becoming light to moderate in the afternoon. Strong to extreme ridgeline winds.
Sunday
Night
Cloudy with light rain and snow increasing after midnight. 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).