A powerful storm system that moved through the Pacific Northwest on Tuesday leaves our region with cooling temperatures, light to occasionally moderate snow showers/convergence, and in some cases strong to extreme westerly winds. Convergence focuses on the area from the Mountain Loop to Stevens Pass with snow totals of 2-6" likely before precipitation tapers off Wednesday evening. Other areas of the west slopes of the Cascades can expect 1-4" of accumulation. The strongest W winds should continue to focus near and east of the Cascades Crest to the south of Snoqualmie Pass. White Pass continues to have strong winds, while extreme winds persist in the Mt. Hood area. These winds should gradually decrease with a more rapid ramp-down as a weak high-pressure ridge moves in Wednesday evening.
The transitory ridge shifts east by Thursday morning with light snow starting up for the Olympics and Mt. Hood areas ahead of an elongated trough in the early morning hours. Light to occasionally moderate snow spreads from SW to NE across the region through the morning with shower activity continuing through the afternoon. SW winds should be in the light to moderate range with light E flow through the mountain gaps.
Temperatures should be fairly steady throughout the forecast period with 2000-3000 ft snow levels.
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
Wednesday
Decreasing clouds with a chance of snow flurries early in the day.
Wednesday
Night
Partly cloudy in the evening, then mostly cloudy with light snow developing by morning.
Wednesday
Cloudy with decreasing light snow showers.
Wednesday
Night
Cloudy.
Wednesday
Decreasing light to moderate snow showers and convergence.
Wednesday
Night
Cloudy.
Wednesday
Decreasing light snow showers.
Wednesday
Night
A chance of flurries or very light snow showers in the evening, with steady light snow developing in thear early morning hours. Strong winds near the Cascade Crest in the morning.
Wednesday
Decreasing light to moderate snow in convergence. Decreasing moderate ridgeline and light to moderate W wind at the Pass.
Wednesday
Night
Light snow showers ending early, then mostly cloudy. Light ridgeline and W switching E winds at the Pass.
Wednesday
Decreasing light to moderate snow in convergence. Decreasing moderate ridgeline and light to moderate W wind at the Pass.
Wednesday
Night
Light snow showers ending early, then mostly cloudy. Light ridgeline and W switching E winds at the Pass.
Wednesday
Snow flurries very near the Cascade Crest, otherwise mostly cloudy.
Wednesday
Night
Partly to mostly clear.
Wednesday
Decreasing light snow showers mainly near the Cascades Crest.
Wednesday
Night
Partly cloudy in the evening, then mostly cloudy overnight.
Wednesday
Decreasing light snow showers confined to near the Cascade Crest.
Wednesday
Night
Partly cloudy in the evening, then mostly cloudy overnight.
Wednesday
Decreasing light snow showers. Extreme ridgeline winds decreasing into the strong range.
Wednesday
Night
Light snow showers in the evening transitioning to light snow after midnight.
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).