The Pacific Northwest sits under a tongue of weak high pressure on Monday morning with a high-pressure ridge building in from offshore through Monday night bringing mostly sunny/clear skies and light winds. A weak disturbance should brush the North Cascades with some mid-level clouds on Monday before clearing out late in the day. Some high clouds from a system over the SW US over have made it as far north as Mt. Hood Monday morning but should retreat southward by late morning. Many locations are experiencing an inversion, which may be strong for some locations east of the Cascade Crest. At Mt. Hood Meadows, 4500 ft temperature was 18F while at 7300, the day started at 31F. East of the Cascades, a deck of low clouds is relatively continuous 3000-4000 ft and decreasing light E flow and decreasing light E flow is sucking these clouds through the lower mountain gaps. After a cold start in many low-lying locations, conditions are milder aloft. When the inversion does mix out by noon on Monday, expect above-freezing temperatures at most pass-level locations and low clouds to dissipate. High temperatures should be in the 30's at 5000 ft throughout the region.
Monday night the region sits under the ridge axis with clear skies before midnight and then some high clouds moving into the region. Temperatures should generally be milder than Sunday night with inversion conditions developing once again, although without E flow.
High and mid-level clouds increase on Tuesday as the next system starts breaking down the ridge. Light precipitation might reach the coastline by the end of the day.
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
Sunny and mild with very light wind.
Monday
Night
Clear skies in the evening, then increasing high clouds thereafter.
Monday
Mostly sunny early with mid-level clouds partially obscuring the sky from mid-morning onwards.
Monday
Night
Clear skies in the evening, then increasing high clouds thereafter.
Monday
Sunny with very light winds.
Monday
Night
Clear skies in the evening, then increasing high clouds thereafter.
Monday
Sunny with very light winds.
Monday
Night
Clear skies in the evening, then increasing high clouds thereafter.
Monday
Sunny aloft with low clouds up to around 4000-4500 ft in the morning. Very light ridgeline winds and decreasing light E flow through the mountain gaps.
Monday
Night
Clear skies in the evening, then increasing high clouds thereafter. Variable pass-level wind becoming light westerly.
Monday
Sunny aloft with low clouds up to around 4000-4500 ft in the morning. Very light ridgeline winds and decreasing light E flow through the mountain gaps.
Monday
Night
Clear skies in the evening, then increasing high clouds thereafter. Variable pass-level wind becoming light westerly.
Monday
Sunny with very light winds. Low clouds up to around 4000-4500 ft in the morning.
Monday
Night
Clear skies in the evening, then increasing high clouds thereafter.
Monday
Sunny with very light winds. Low clouds up to around 4000-4500 ft in the morning.
Monday
Night
Clear skies in the evening, then increasing high clouds thereafter.
Monday
Sunny with very light winds. Low clouds up to around 4000-4500 ft in the morning.
Monday
Night
Clear skies in the evening, then increasing high clouds thereafter.
Monday
Sunny with light winds.
Monday
Night
Clear skies in the evening, then increasing high clouds thereafter.
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).