Showers in brisk westerly flow will continue this morning with locally heavier showers near Mt Hood and near areas of convergence along the west slopes of the Cascades from I-90 and north through Whatcom County. The convergence zone(s) will drift north and weaken through mid-day. This morning's heaviest accumulations will fall over the western sections of the Cascades in Whatcom/Skagit and Snohomish Counties as well as Mt Hood, where an additional 3-6" of snow may fall. We'll see lighter accumulations elsewhere.
Showers will become scattered and lighter this afternoon. Low clouds will stick along the Olympics, Mt Hood area, and the west slopes of the Cascades and Passes but there will be sunbreaks. You won't have to travel too far east of the Cascade crest to find much sunnier skies Tuesday afternoon along with slightly higher freezing levels.
We'll have a brief reprieve tonight as upper level ridging passes inland. A stronger frontal system will start to spread warm frontal precipitation inland during the morning hours. Cool easterly flow will help nudge snow levels down to 2500' across much of the Washington Cascades at the onset of precipitation Wednesday morning. Snow levels will inch up during the day, and pop around 4000-4500' in the late afternoon as a weakening cold front pushes through. Precipitation amounts look to be in the 0.25-0.75" range during the day, with the highest totals likely for Mt Hood, Crystal/Paradise and the Mt Baker area. Mt Hood will be the windiest and mildest location during this storm.
Weather Forecast
Olympics
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West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
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Tuesday
Cloudy with scattered light rain and snow showers, becoming partly to mostly cloudy with isolated showers in the afternoon.
Tuesday
Night
Mostly cloudy with increasing high clouds in the evening. Then cloudy with light rain and snow developing late tonight. Moderate ridgeline winds.
Tuesday
Cloudy light to occasionally moderate rain and snow showers this morning, becoming mostly cloudy with sunbreaks and scattered light showers in the afternoon.
Tuesday
Night
Mostly cloudy with increasing high clouds overnight. Moderate ridgeline winds after midnight.
Tuesday
Cloudy light to occasionally moderate rain and snow showers this morning, becoming mostly cloudy with sunbreaks and scattered light showers in the afternoon. Moderate ridgeline winds.
Tuesday
Night
Mostly cloudy with increasing high clouds overnight.
Tuesday
Cloudy with scattered light rain and snow showers this morning, becoming mostly cloudy with sunbreaks and isolated light showers in the afternoon. Moderate ridgeline winds.
Tuesday
Night
Partly to mostly cloudy with increasing high clouds in the evening. Then cloudy with light rain and snow developing late tonight. Moderate ridgeline winds after midnight.
Tuesday
Cloudy light to occasionally moderate rain and snow showers this morning, becoming mostly cloudy with sunbreaks and scattered light showers in the afternoon. Moderate ridgeline and Pass level W winds.
Tuesday
Night
Mostly cloudy. Light E Pass level winds and light to moderate S-SE ridgeline winds.
Tuesday
Cloudy light to occasionally moderate rain and snow showers this morning, becoming mostly cloudy with sunbreaks and scattered light showers in the afternoon. Moderate ridgeline and Pass level W winds.
Tuesday
Night
Mostly cloudy with increasing high clouds overnight. Light E Pass level winds and light to moderate S-SE ridgeline winds.
Tuesday
Mostly cloudy with scattered light rain and snow showers this morning, becoming partly to mostly sunny this afternoon. Cloudier near the Cascade crest. Moderate ridgeline winds.
Tuesday
Night
Partly to mostly cloudy with increasing high clouds overnight.
Tuesday
Mostly cloudy with scattered light rain and snow showers this morning, becoming partly to mostly sunny this afternoon. Cloudier near the Cascade crest. Moderate ridgeline winds.
Tuesday
Night
Partly to mostly cloudy with increasing high clouds overnight. Moderate ridgeline winds after midnight.
Tuesday
Mostly cloudy with scattered light rain and snow showers this morning, becoming partly to mostly sunny this afternoon. Cloudier near the Cascade crest. Moderate ridgeline winds.
Tuesday
Night
Partly to mostly cloudy with increasing high clouds in the evening. Then cloudy with light rain and snow developing late tonight. Moderate ridgeline winds after midnight.
Tuesday
Cloudy light to occasionally moderate rain and snow showers this morning, becoming mostly cloudy with sunbreaks and scattered light showers in the afternoon. Strong ridgeline winds becoming moderate in the afternoon.
Tuesday
Night
Partly to mostly cloudy with increasing high clouds in the evening. Then cloudy with light rain and snow developing late tonight. Moderate 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).