Leftover scattered showers will linger across the west slopes of the Cascades, Olympics and Mt Hood this morning, tapering off in a south to north fashion during the day. Clouds and isolated showers should linger the longest from about the Mt Loop Hwy and north to the Canadian border. Sunshine should break out south of I-90 on both sides of the Cascades down to Mt Hood today. An incoming frontal system will approach quickly overnight and push through the Cascades by late Tuesday morning. Precipitation rates should increase rapidly in the morning with moderate post-frontal showers in the afternoon. For areas near Hwy 2 and further south, this storm will feature a warming trend after the frontal passage as relatively milder Pacific air becomes mixed throughout the region. Strong post-frontal westerly ridgeline winds are also expected. The warming trend will be more subtle for the North Cascades on Tuesday.
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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Monday
Mostly cloudy with scattered light showers in the morning, becoming partly sunny in the afternoon.
Monday
Night
Cloudy with rain and snow developing after midnight.
Monday
Cloudy with scattered light showers in the morning, becoming mostly cloudy with isolated showers in the afternoon.
Monday
Night
Cloudy with rain and snow developing after midnight.
Monday
Cloudy with scattered light showers in the morning, becoming mostly cloudy with isolated showers in the afternoon.
Monday
Night
Cloudy with rain and snow developing after midnight.
Monday
Mostly cloudy with scattered light showers in the morning, becoming partly to mostly cloudy in the afternoon.
Monday
Night
Cloudy with rain and snow developing late.
Monday
Mostly cloudy with scattered light showers in the morning, becoming partly to mostly cloudy in the afternoon. Light west winds at Pass level.
Monday
Night
Cloudy with rain and snow developing late. Light to moderate east winds at Pass level.
Monday
Mostly cloudy with scattered light showers in the morning, becoming partly to mostly cloudy in the afternoon. Light west winds at Pass level.
Monday
Night
Cloudy with rain and snow developing late. Light to moderate east winds at Pass level.
Monday
Mostly cloudy with scattered light showers in the morning, becoming mostly cloudy in the afternoon.
Monday
Night
Cloudy with rain and snow developing late.
Monday
Mostly cloudy with scattered light showers in the morning, becoming partly sunny in the afternoon.
Monday
Night
Cloudy.
Monday
Mostly cloudy with scattered light showers in the morning, becoming partly sunny in the afternoon.
Monday
Night
Cloudy.
Monday
Mostly cloudy with scattered light showers in the morning, becoming partly to mostly sunny 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).