Brrrr! We're off to a chilly start this morning with many of our mountain weather stations reporting temperatures in the mid-teens. You may see some low-clouds or valley fog to start the day, but these should quickly dissipate. A high-pressure ridge in the eastern Pacific will drive our weather for the next couple of days. After a sunny morning, on-shore flow, warming temperatures, and lingering low-level moisture should result in a few puffy clouds developing along the West Slopes of the Cascades and passes. For the mountains today expect mild temperatures and generally light winds.
Overnight the high-pressure shifts inland and drags much warmer and drier air with it. Clear skies will allow for temperature inversions in many of the mountain valleys and passes. As the ridge axis passes overhead, easterly flow will develop through the mountain gaps. However, the flattening ridge and lack of cold air in eastern Washington should minimize the impacts of the east winds.
Temperature inversions should quickly mix out on Wednesday morning sending freezing levels soaring especially for the central and southern portions of the forecast region. This will result in the warmest day of the week. High temperatures should easily reach into the 40s for most of our mountain locations. After a sunny start, look for high clouds and increasing alpine winds to spread over the region in the afternoon ahead of an approaching Pacific storm.
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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Tuesday
Mostly sunny in the morning becoming partly cloudy in the afternoon.
Tuesday
Night
Mostly clear with a few high thin clouds.
Tuesday
Mostly sunny becoming partly to mostly cloudy in the afternoon.
Tuesday
Night
Mostly clear with high thin clouds possible.
Tuesday
Mostly sunny becoming partly to mostly cloudy in the afternoon.
Tuesday
Night
Mostly clear with high thin clouds possible.
Tuesday
Mostly sunny patchy fog and low clouds in the morning. Becoming partly cloudy in the afternoon.
Tuesday
Night
Mostly clear.
Tuesday
Mostly sunny with patchy low clouds in the morning. Increasing clouds in the afternoon.
Tuesday
Night
Mostly clear with some high thin clouds possible. East flow developing overnight.
Tuesday
Mostly sunny patchy low clouds in the morning. Becoming partly cloudy in the afternoon.
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).