A warm front continues to advance across WA as it drops lowland rain and mountain snow on both sides of the Cascades, the Olympics, and Mount Hood. Snow levels will rise a bit during the day before the trailing cold front brings them back down. Expect wet snow, maybe mixing with rain, at trailhead and pass elevations. The daytime portion of this event favors Mount Baker, the West South, and Mount Hood, with generally modest accumulations elsewhere. An important feature of the storm is upper-mid and upper-elevation winds. While the 5000' wind speeds are in the moderate range in most locations, wind speed is increasing rapidly with elevation, delivering strong and gusty winds to the upper slopes, as exemplified by the 50 mph sustained winds at the top of Crystal Mountain.
There is a good deal of uncertainty in how the post-frontal period takes shape this evening. Many model solutions have a healthy dose of post-frontal precipitation focused on the passes, Mountain Loop, West and East South, and Mount Hood. We'll have a deeper look at that in this evening's forecast. Regardless, precipitation tapers overnight into Thursday as a short-lived ridge tries to build over Washington. This ridge will have to duke it out with a warm front passing by to the north that may keep some showers near the coast and in the northern portion of the forecast area on Thursday.
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
Light rain and snow. Moderate and gusty south winds trending west.
Wednesday
Night
Decreasing snow showers with moderate westerly winds.
Wednesday
Rain and snow, heavy at times. Moderate to strong southerly winds veering west.
Wednesday
Night
Decreasing snow showers with moderate to strong westerly winds.
Wednesday
Rain and snow, with locally heavier accumulations. Moderate southerly winds.
Wednesday
Night
Snow showers with moderate to strong westerly winds.
Wednesday
Rain and snow will be heavy at times, especially on the volcanoes. Moderate southerly winds are strong and gusty near the crest and at higher elevations.
Wednesday
Night
Snow will be heavy at times, especially on the volcanoes. Moderate westerly winds, stronger near the crest.
Wednesday
Snow showers with moderate south winds at ridgeline and moderate southeast winds at pass level.
Wednesday
Night
Snow showers, may be heavier at times. Moderate to strong westerly winds.
Wednesday
Rain and snow showers with moderate south winds at ridgeline, and moderate southeast winds at pass level .
Wednesday
Night
Rain and snow, heavy at times. Moderate to strong westerly winds at pass and ridgeline.
Wednesday
Snow showers with light to moderate southeasterly winds.
Wednesday
Night
Light snow showers with moderate westerly winds.
Wednesday
Snow with moderate to strong southerly winds.
Wednesday
Night
Decreasing snow showers with strong westerly winds.
Wednesday
Snow showers with moderate south winds veering west.
Wednesday
Night
Snow showers with moderate to strong westerly winds.
Wednesday
Heavy snow with strong westerly winds.
Wednesday
Night
Occasionally heavy snow in the evening, decreasing overnight with increasing and strong westerly 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).