An upper low sliding south off the Pacific Northwest Coastline forms a rapidly deepening surface low off the Oregon Coast. The low will rotate increasing high cloud cover into the Pacific Northwest today, with more clouds in the southern parts of the region. ESE winds will also ramp up as the low deepens and a warm frontal feature approaches from the south.
Light rain and snow reach the Mt Hood area first during the evening hours, spreading into the ES Cascades overnight. ESE winds peak in the moderate to strong range for Mt Hood and the southern Washington Cascades during the evening hours as the frontal feature moves over the area. The band of most intense winds shifts into the central Washington Cascades overnight into Tuesday. Light rain and snow should spread slightly further north along the east slopes of the Cascades with light to moderate rain and snow peaking early Tuesday for Mt. Hood.
Temperatures moderate during the forecast period, particularly west of the Cascade Crest with the downslope winds. Expect the strongest winds during this period to be near the Cascades Crest, but also in the western foothills of the Cascades.
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
Filtered sunshine with a few scatttered clouds in the afternoon.
Monday
Night
High clouds lowering and thickening.
Monday
Mostly sunny with popcorn cumulus clouds in the afternoon.
Monday
Night
Mostly clear in the evening with increasing high clouds overnight.
Monday
Mostly sunny in the morning with scattered clouds in the afternoon.
Monday
Night
High clouds lowering and thickening.
Monday
Filtered sunshine with increasing scattered low clouds.
Monday
Night
Cloudy. Moderate to strong ridgeline winds (very strong gusts).
Monday
Filtered sunshine with increasing scattered low clouds. Increasing light to moderate ridgeline and E wind at the Pass.
Monday
Night
Cloudy. Increasing moderate to strong ridgeline winds. Increasing moderate E wind at the Pass.
Monday
Filtered sunshine with increasing scattered low clouds. Increasing light to moderate ridgeline and E wind at the Pass.
Monday
Night
Cloudy. Increasing moderate to strong (gusting extreme) ridgeline winds. Increasing moderate E wind at the Pass.
Monday
Mostly sunny with scattered cumulus clouds.
Monday
Night
Increasing high clouds.
Monday
Filtered sunshine with scattered cumulus clouds.
Monday
Night
High clouds lowering and thickening.
Monday
Filtered sunshine, sky becomes obscured late in the day.
Monday
Night
High clouds lowering and thickening in the evening with light rain or snow developing in southern parts of the area overnight.
Monday
Filtered sunshine, sky becomes obscured late in the day.
Monday
Night
Cloudy with light rain or snow possibly becomes moderate overnight. Moderate to strong ridgeline winds (extreme gusts).
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).