A strong cold front associated with a low pressure center in Alberta continues to impact our region with heavy snowfall, strong winds, and plummeting temperatures. The southward march of the front targets the heaviest frontal precipitation along with strong ridgeline winds to Mt. Hood and the southernmost Washington Cascades during the morning hours. A cold and very unstable air mass behind the front creates conditions ripe for locally heavy snowfall. A slow-moving convergence band formed over Snoqualmie Pass just following frontal passage and will continue to bring strong winds, heavy snow, and blizzard conditions well into the morning hours. High-resolution weather models suggest this convergence band may shift south of Snoqualmie by mid-morning, but other bands will likely re-form and continue to impact the central Washington Cascades. Instability showers will also bring locally intense snow squalls to the west slopes of the Cascades throughout the day; and some shower activity and convergence will spill over onto the east slopes of the Cascades. The north Cascades will experience lighter winds and lighter snow showers than areas further south.
A broad upper trough continues to settle into the northwestern United States, continuing to usher in cold air. Ridgeline winds ease over Washington state by the evening hours and also relent into the moderate range around Mt. Hood. Mostly light snowshowers continue over Washington, but moderate to heavy snow showers with significant accumulations continue due to better mountain enhancement over Mt. Hood.
Winds shift NNW on Monday and snow showers should become light across the region as the trough shifts east and flow becomes NNW aloft. Temperatures will be significantly below normal thorughout the time period with snow levels approaching sea level in many areas by Monday morning.
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
Sunday
Light, but locally intense snow showers. Significantly colder.
Sunday
Night
Light, but locally intense snow showers. Cold.
Sunday
Light, but locally intense snow showers increasing slightly during the afternoon. Significantly colder.
Sunday
Night
Decreasing light, but locally intense snow showers. Cold.
Sunday
Moderate and locally intense snow showers and convergence banding. Significantly colder.
Sunday
Night
Light to moderate snow showers/convergence becoming light. Cold.
Sunday
Moderate and locally intense snow showers. Significantly colder.
Moderate and locally intense snow showers/convergence banding. Colder. Decreasing moderate ridgeline winds and moderate W winds with strong gusts at the Pass.
Sunday
Night
Light to moderate snow showers/convergence becoming light. Cold. Light ridgeline and W wind at the Pass.
Sunday
Moderate and locally heavy convergence banding becoming more showery later in the day. Colder. Moderate ridgeline winds and strong W winds with extreme gusts at the Pass during convergence banding; may ease during the afternoon.
Sunday
Night
Light to moderate snow showers/convergence becoming light. Cold. Light ridgeline and W wind at the Pass.
Sunday
Light snow showers. Colder.
Sunday
Night
Light snow showers mainly near the Cascade Crest. Cold.
Sunday
Light, but locally intense snow showers / convergence banding. Colder.
Sunday
Night
Light snow showers and convergence spillover. Cold.
Sunday
Moderate snow quickly transitions to light snow showers as temperatures drop sharply. Decreasing moderate ridgeline winds.
Sunday
Night
Light to occasionally moderate snow showers. Cold.
Sunday
Heavy snow in the morning (rain below 4000 ft), transitioning to moderate snow showers by afternoon as temperatures plummet. Decreasing strong ridgeline winds with extreme gusts.
Sunday
Night
Moderate to heavy snow showers. Cold. Moderate winds.
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).