A strong low drops south off the Oregon Coastline today. Wrap-around winds will impact the entire region with moderate to occasionally strong ridgeline winds having peaked Monday night through early Tuesday but should decrease only very gradually during the day. Moisture wrapping around should continue to bring light to moderate rain and snow to Mt Hood. The rising air along the east slopes of the Cascades could continue to bring some very light and sporadic snow extending northward as far as Washington Pass along the east slopes of the Cascades on Tuesday.
Light snowfall increases for the east slopes of the Washington Cascades as upper-level winds shift from SSE to E Tuesday night. Expect several inches of snow for places like Mission Ridge and areas east of White Pass.
The upper low exits far enough south on Wednesday that the precipitation tapers off, but expect just enough instability for some scattered rain or snow showers over the southern Cascades continuing into the afternoon. WIth increased sunshine and weak ridging moving in from the north, expect freezing levels in some areas to rise to around 5500 ft.
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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Tuesday
Mostly cloudy with light rain and snow developing for the eastern Olympics in the afternoon.
Tuesday
Night
Light rain and snow in the evening, then becoming mostly cloudy.
Tuesday
Mostly sunny with decreasing high clouds.
Tuesday
Night
Partly cloudy.
Tuesday
Filtered sunshine in the morning, then becoming mostly cloudy in the afternoon.
Tuesday
Night
Cloudy.
Tuesday
Cloudy with very light rain or snow at times. Moderate ridgeline winds (strong at times near the Cascade Crest) with strong gusts.
Tuesday
Night
Cloudy with periods of light rain and snow.
Tuesday
Mostly cloudy. Moderate ridgeline and E wind at the Pass.
Tuesday
Night
Mostly cloudy with light rain or snow at times. Decreasing light to moderate ridgeline and E wind at the Pass.
Tuesday
Mostly cloudy with a chance of very light rain or snow in the morning. Moderate ridgeline and E wind at the Pass.
Tuesday
Night
Very light rain or snow possible in the evening, then remaining cloudy overnight. Decreasing light to moderate ridgeline and E wind at the Pass.
Tuesday
Periods of light rain or snow possible at times. Moderate ridgeline winds.
Tuesday
Night
Cloudy with a slight chance of light rain or snow.
Tuesday
Cloudy with increasing chances for very light rain or snow. Moderate ridgeline winds.
Tuesday
Night
Light rain or snow at times.
Tuesday
Light rain or snow at times. Moderate ridgeline winds.
Tuesday
Night
Light to occasionally moderate rain or snow at times.
Tuesday
Light to moderate snow. Moderate ridgeline winds at times.
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).