Active weather continues across the Cascades this morning with a southwest-to-northeast flow pattern in place. Mount Baker continues to receive the heaviest precipitation, while lighter rain and snow have spread across the west side. Little moisture is reaching areas east of the crest. Weather stations are reporting generally light to moderate wind speeds. Snow levels remain around 4,500–5,000 feet this morning.
Today, flow direction will shift from SW to W, and later NW, as an upper-level trough digs in over the region. Cooler air will follow this transition, lowering snow levels Wednesday night into Thursday to most mountain passes and trailheads. The NWS has issued a Winter Weather Advisory for the central and southern Cascades through Thursday afternoon to address snowfall near the passes. There is high confidence that a convergence zone will develop Wednesday afternoon between Stevens Pass and Snoqualmie Pass, before drifting south over Snoqualmie Pass later in the day. This will likely produce locally heavier precipitation and a slight chance of thunderstorms within the convergence zone.
Gusty winds will accompany the flow transition, with moderate to strong winds expected along ridgelines Wednesday afternoon into Thursday. Particularly strong winds are forecast for Mount Hood, through the passes, and into the East Central zone.
Snowfall will continue on Thursday, but with lessening moisture to work with. Precipitation will taper off, with slightly warmer temperatures developing by late afternoon.
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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Wednesday
Rain and mountain snow. Low clouds in the afternoon.
Wednesday
Night
Rain and snow. Light to moderate ridgeline wind.
Wednesday
Rain and mountain snow. Low clouds in the afternoon. Light to moderate ridgeline wind.
Wednesday
Night
Rain and snow. Light to moderate ridgeline wind.
Wednesday
Rain and mountain snow. Low clouds in the afternoon. Light to moderate ridgeline wind.
Wednesday
Night
Rain and snow. Moderate ridgeline wind.
Wednesday
Rain and mountain snow, heavier near the crest. Light to moderate ridgeline wind.
Wednesday
Night
Rain and snow. Moderate ridgeline wind.
Wednesday
Rain and mountain snow. Light to moderate ridgeline, and W wind at the Pass.
Wednesday
Night
Rain and snow. Light to moderate ridgeline, and W wind at the Pass.
Wednesday
Rain and mountain snow. Light to moderate ridgeline, and W wind at the Pass.
Wednesday
Night
Rain and snow. Moderate to strong ridgeline, and W wind at the Pass.
Wednesday
Light rain and mountain snow. Thinning clouds east of the crest. Chance of partial clearing in the afternoon. Light to moderate ridgeline wind.
Wednesday
Night
Light rain and snow. Moderate ridgeline wind.
Wednesday
Light rain and mountain snow. Thinning clouds east of the crest. Chance of partial clearing in the afternoon. Moderate ridgeline wind.
Wednesday
Night
Chance of rain and snow. Moderate to strong ridgeline wind.
Wednesday
Occasional rain and mountain snow. Thinning clouds east of the crest. Chance of partial clearing in the afternoon. Light to moderate ridgeline wind.
Wednesday
Night
Chance of rain and snow. Moderate to strong ridgeline wind.
Wednesday
Rain and mountain snow. Moderate to strong ridgeline wind. Low clouds in the afternoon, with a chance of partial clearing to the east.
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).