A weak front currently positioned along the Washington coast this morning will slowly move inland today, passing through the Cascades mid to late afternoon. After a very mild Tuesday night with mountain temperatures holding in the 40s across much of the region, temperatures and freezing levels will begin a slow decline this morning, falling more rapidly with the onset of precipitation. The Olympics and northwest Cascades will be the first to see precipitation later this morning along with strong southerly winds ahead of the front. Light rain and snow will take their time moving to the Cascade crest this afternoon. Mt Hood will see little to no precipitation but will see some clouds along the lower half of the mountain as well as increasing winds. The Mt Baker area should pick up several inches of wet snow above 4500-5000' by 5 pm today, with much lighter amounts elsewhere.
After the front swings through, we'll see a brief period of post-frontal showers including a Puget Sound Convergence zone aimed into the central Cascades. This won't be a memorable Convergence zone event as gusty post-frontal westerly winds quickly ease off Wednesday night and showers come to an abrupt end with drier and cooler air quickly moving into the region. Mt Hood won't see a meaningful cool-down overnight and if they see any precipitation in the evening, it could come in the form of light freezing rain.
An upper level ridge will quickly build offshore late Wednesday night and shift inland and east of the Cascades Thursday morning. We'll have a dry, fair weather day on Thursday with rebounding temperatures and a fair bit of high clouds passing overhead.
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
Cloudy with periods of light rain and snow, becoming partly sunny in the afternoon. Moderate to strong ridgeline winds.
Wednesday
Night
Mostly clear.
Wednesday
Cloudy with light rain and snow developing later this morning, becoming light to moderate in the afternoon. Strong ridgeline winds.
Wednesday
Night
Mostly cloudy with scattered light rain and snow showers tapering off in the evening, then partly cloudy.
Wednesday
Cloudy with light rain and snow developing later this morning, becoming light to occasionally moderate in the afternoon. Moderate to strong ridgeline winds in the afternoon.
Wednesday
Night
Mostly cloudy with light rain and snow showers tapering off in the evening, then partly cloudy.
Wednesday
Cloudy. Light rain and snow developing in the afternoon. Moderate ridgeline winds increasing in the afternoon.
Wednesday
Night
Mostly cloudy with scattered light rain and snow showers tapering off in the evening, then partly cloudy.
Wednesday
Cloudy. Light rain and snow developing in the afternoon. Light east winds at Pass level becoming moderate west winds late.
Wednesday
Night
Mostly cloudy with light rain and snow showers tapering off in the evening, then partly cloudy. Moderate west winds decreasing overnight.
Wednesday
Cloudy. Light rain and snow developing in the afternoon. Light east winds at Pass level becoming moderate west winds late.
Wednesday
Night
Mostly cloudy with light rain and snow showers tapering off in the evening, then partly cloudy. Moderate west winds decreasing overnight.
Wednesday
Cloudy. Light rain and snow developing late in the afternoon. Moderate ridgeline winds increasing in the afternoon.
Wednesday
Night
Mostly cloudy in the evening, then mostly clear after midnight. Moderate to strong ridgeline winds decreasing after midnight.
Wednesday
Cloudy. Light rain and snow developing late in the afternoon near the Cascade crest. Moderate to strong ridgeline winds increasing in the afternoon.
Wednesday
Night
Mostly cloudy in the evening, then mostly clear after midnight. Strong ridgeline winds decreasing after midnight.
Wednesday
Cloudy. Chance of light rain and snow near the Cascade crest in the afternoon. Moderate to strong ridgeline winds increasing in the afternoon.
Wednesday
Night
Mostly cloudy in the evening, then mostly clear after midnight. Moderate to strong ridgeline winds decreasing after midnight.
Wednesday
Partly to mostly cloudy, with clouds mainly lower to mid-mountain. Chance of light rain or snow late in the day. Moderate to strong ridgeline winds increasing in the afternoon.
Wednesday
Night
Mostly cloudy with a chance of light rain, snow of freezing rain in the evening, then mostly clear after midnight. Strong ridgeline 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).