A high-pressure will bring dry and quiet weather to the region through Tuesday. A broad region of high pressure centered off the coast of California extends a ridge axis into our nearshore waters, leaving our region with dry northerly flow aloft through Monday night. This should bring sunny weather and mostly light winds on Monday. Higher ridgetop locations above 6500 ft are an exception and moderate northerly winds may continue at these elevations. Temperatures at NWAC stations are in the upper teens to lower thirties early Monday morning, with subtle inversions in some areas. Temperatures should be mild in most areas by the afternoon. Monday night, clear skies prevail in the evening with some high clouds moving into the region after midnight.
The ridge flattens on Tuesday due to a system mostly impacting central British Columbia. A shallow inversion overnight and slight E gradient will keep valley locations in the Cascades chilly into the mid-morning hours when the inversion is expected to mix out. As the weakening tail of this frontal system approaches our region on Tuesday, expect filtered sunshine and a shift to westerly and increasing light to moderate ridgeline winds.
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
Mostly sunny.
Monday
Night
Mostly clear with increasing high clouds after midnight.
Monday
Mostly sunny.
Monday
Night
Mostly clear with increasing high clouds after midnight.
Monday
Mostly sunny.
Monday
Night
Mostly clear with increasing high clouds after midnight.
Monday
Mostly sunny.
Monday
Night
Mostly clear with increasing high clouds after midnight.
Monday
Mostly sunny.
Monday
Night
Mostly clear with increasing high clouds after midnight.
Monday
Mostly sunny.
Monday
Night
Mostly clear with increasing high clouds after midnight.
Monday
Mostly sunny.
Monday
Night
Mostly clear with increasing high clouds after midnight.
Monday
Mostly sunny.
Monday
Night
Mostly clear with increasing high clouds after midnight.
Monday
Mostly sunny.
Monday
Night
Mostly clear with increasing high clouds after midnight.
Monday
Mostly sunny.
Monday
Night
Mostly clear with increasing high clouds in the early morning hours.
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).