An atmospheric river will deliver a punch of moisture this morning before lifting north in the afternoon, heaviest near and north of I-90. The north Cascades will be the slowest to warm, but snow levels will soar for all areas today into the 12,500' range for Mt Hood, to the 7000-8000' near Mt Hood. Westerly winds will be strong. As the frontal boundary lifts north, look for partial clearing, most pronounced near and south of I-90.
This warm, wet pattern will continue as the frontal boundary sags back southwards tonight and lingers over us tomorrow. Snow levels will be well above the levels we care about, with rain up to most mountain tops. Westerly winds will increase further tonight into Tuesday. There's quite a bit of forecast uncertainty about just how heavy the rain will be on Tuesday.
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
Cloudy with light to moderate rain in the morning, then mostly cloudy in the afternoon. Strong ridgeline winds.
Monday
Night
Cloudy in the evening, then light rain after midnight. Strong ridgeline winds.
Monday
Light to moderate rain and snow through early afternoon, then mostly cloudy with periods of rain in the late afternoon. Strong ridgeline winds.
Monday
Night
Cloudy in the evening, then light to moderate rain after midnight. Strong ridgeline winds.
Monday
Light to moderate rain and snow through mid-day, then mostly cloudy with periods of rain in the afternoon. Strong ridgeline winds.
Monday
Night
Mostly cloudy in the evening, then light to moderate rain after midnight. Strong ridgeline winds.
Monday
Light to moderate rain and snow through mid-day, then partly to mostly cloudy with a chance of rain in the afternoon. Strong ridgeline winds.
Monday
Night
Cloudy in the evening, then light rain after midnight. Strong ridgeline winds.
Monday
Light to moderate rain and snow through mid-day, then mostly cloudy with a chance of rain in the afternoon. Moderate to strong W winds at Pass level, strong at ridgeline.
Monday
Night
Cloudy in the evening, then light rain after midnight. Moderate to strong W winds at Pass level, strong at ridgeline.
Monday
Light to moderate rain and snow through mid-day, then mostly cloudy with a chance of rain in the afternoon. Moderate to strong W winds at Pass level, strong at ridgeline.
Monday
Night
Cloudy in the evening, then light rain after midnight. Moderate to strong W winds at Pass level, strong at ridgeline.
Monday
Light to occasionally moderate rain and snow through mid-day, heaviest near the Cascade crest, then partly to mostly cloudy in the afternoon. Strong ridgeline winds.
Monday
Night
Cloudy in the evening, then light rain after midnight near the Cascade crest. Strong ridgeline winds.
Monday
Light to occasionally moderate rain and snow through mid-day, heaviest near the Cascade crest, then partly to mostly sunny in the afternoon. Strong ridgeline winds.
Monday
Night
Partly to mostly cloudy in the evening, then light rain after midnight near the Cascade crest. Strong to extreme ridgeline winds.
Monday
Light to occasionally moderate rain and snow through mid-day, heaviest near the Cascade crest, then partly to mostly sunny in the afternoon. Strong ridgeline winds.
Monday
Night
Partly to mostly cloudy. Strong to extreme ridgeline winds.
Monday
Cloudy with a chance of light rain this morning, then mostly sunny. Strong ridgeline winds.
Monday
Night
Partly to mostly cloudy. 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).