A large upper level ridge parked offshore continues to bring dry, and relatively warm conditions across the Pacific Northwest. Dense valley fog is blanketed over western Washington this morning, with low level clouds east of the Crest. A strong temperature inversion has also taken hold, allowing for very cold temperatures in low-lying areas against the mountains, and progressively warmer temperatures at higher elevations.
A weak disturbance moving over the Rockies will carry some short-lived thin high clouds over the Cascades on Tuesday, along with NW wind aloft. Cloud cover will peak midday in the form of filtered sunshine, and begin clearing in northern zones by the late afternoon. Mt Hood will see lingering clouds through most of Tuesday night into Wednesday morning. Ridge tops near mountain gaps could see flip-flopping wind direction between E and W depending on the height of the inversion. East flow will continue to bring cold air into the mountain gaps through Wednesday.
Overall, high pressure will persist into Wednesday, with mostly clear skies and low level clouds east of the Cascades. More thin, high clouds may pass over the region Wednesday afternoon.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
Use dropdown to select your zone
Tuesday
High clouds, clearing in the afternoon. Cooling trend through the day. Temperature inversion below 6,000 feet.
Tuesday
Night
Clear. Cooling temperatures.
Tuesday
High clouds, clearing in the afternoon. Cooling trend through the day. Temperature inversion below 6,000 feet.
Tuesday
Night
Clear. Cooling temperatures.
Tuesday
High clouds with a cooling trend through the day. Temperature inversion trapping cold air in the valleys.
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).