An occluded front will spread light precipitation from south to north today with a short-lived burst of precipitation as it passes through. Areas south of I-90 will transition to broken clouds and scattered showers in the afternoon while the front slides towards the Canadian border in the afternoon. Southerly winds will increase this morning and become moderate to strong SW then W later this afternoon and evening. Freezing levels will peak around 4500' today and then fall to 3500-4000' with the onset of precipitation.
Post-frontal showers will mainly focus on the northwest Cascades/Mt Baker area through midnight as snow levels fall to 2000-2500' Tuesday night. Scattered light showers will peter out for other areas more quickly tonight.
On Wednesday, a broad upper level trough of low pressure will be positioned offshore. This large scale weather feature should spill a fair amount of mid-level clouds (scattered to broken skies) northwards during the day, along with a chance of showers, especially in the afternoon. Snow levels will peak between 4000-5000' on Wednesday.
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
Light to occasionally moderate rain and snow becoming scattered light showers this afternoon. Moderate to strong ridgeline winds.
Cloudy this morning, then light to occasionally moderate rain and snow developing this afternoon. Moderate to occasionally strong ridgeline winds.
Tuesday
Night
Cloudy with light to moderate rain and snow showers decreasing overnight. Moderate ridgeline winds decreasing overnight.
Tuesday
Cloudy this morning, then light to occasionally moderate rain and snow developing this afternoon. Light to moderate ridgeline winds increasing in the afternoon.
Light to occasionally moderate rain and snow developing this morning, then mostly cloudy with scattered light showers in the afternoon. Light to moderate ridgeline winds becoming strong in the afternoon.
Cloudy this morning, then light to occasionally moderate rain and snow developing this afternoon. Light to moderate SSE ridgeline winds becoming moderate SW this afternoon. Light E Pass level winds becoming moderate W late.
Tuesday
Night
Mostly cloudy with scattered light evening showers. Moderate ridgeline and Pass level W winds decreasing overnight.
Tuesday
Cloudy this morning, then light to occasionally moderate rain and snow developing this afternoon. Light to moderate SSE ridgeline winds becoming moderate to strong SW this afternoon. Light E Pass level winds becoming moderate W late.
Tuesday
Night
Mostly cloudy with scattered light evening showers. Moderate ridgeline and Pass level W winds decreasing overnight.
Tuesday
Cloudy this morning, then light to occasionally moderate rain and snow developing this afternoon. Light to moderate ridgeline winds increasing this afternoon.
Tuesday
Night
Mostly cloudy with scattered light evening showers. Moderate to strong ridgeline winds decreasing overnight.
Tuesday
Cloudy this morning, then light to occasionally moderate rain and snow developing this afternoon. Light to moderate ridgeline winds increasing this afternoon.
Tuesday
Night
Mostly cloudy with scattered light evening showers. Moderate to strong ridgeline winds decreasing overnight.
Tuesday
Light to occasionally moderate rain and snow developing this morning, then mostly cloudy with scattered light showers in the afternoon. Light to moderate ridgeline winds increasing this afternoon.
Tuesday
Night
Mostly cloudy with scattered light evening showers. Moderate to strong ridgeline winds decreasing overnight.
Tuesday
Light to occasionally moderate rain and snow developing this morning, then mostly cloudy with scattered light showers in the afternoon. Moderate ridgeline winds becoming strong in the afternoon.
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).