A weak front dissipates this morning as it slides SE across the central Washington Cascades on Sunday. The front features a band of low-level convergence associated with an increasingly disorganized band of rain and snow impacting the west slopes of the Cascades from HWY 2 to I-90. This band of rain and snow should shift southward across the central and southern Washington Cascades but continues to weaken. Satellite imagery depicts the back edge of the upper-level front passing over the San Juan Islands, with clearing skies to the north. With mostly cloudy skies limiting daytime heating, cooling with the frontal system should result in a continued gradual lowering of snow levels during the day. The upper-level trough shifts over the area in the afternoon and may spawn isolated rain or snow shower activity across Washington State.
Lingering snow flurries continue into the evening hours as winds shift northerly behind the trough. Clearing skies combined with mostly light winds should allow temperatures to drop significantly overnight.
Monday appears to be mostly clear and sunny with temperatures rebounding nicely in the afternoon after a cool start to the day.
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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Sunday
Mostly cloudy early, then becoming partly to mostly sunny.
Sunday
Night
Mostly clear.
Sunday
Mostly cloudy with snow flurries or isolated snow showers at times. More sun likely during the mid-day hours.
Sunday
Night
Scattered clouds early, then becoming mostly clear.
Sunday
Light rain and snow early in the southern part of the zone. Then isolated rain and snow showers possible.
Sunday
Night
Partly cloudy, then becoming mostly clear overnight.
Sunday
Mostly cloudy with periods of light rain and snow.
Sunday
Night
Partly cloudy with very light snow flurries early, then becoming mostly clear overnight.
Sunday
Light rain and snow early with weak low-level convergence, then mostly cloudy with a chance for isolated rain or snow showers in the afternoon. Light W wind at the Pass.
Sunday
Night
Partly cloudy, then becoming mostly clear overnight. Light W wind at the Pass.
Sunday
Light rain and snow with weak low-level convergence during the morning hours, then mostly cloudy with a chance for isolated rain or snow showers in the afternoon. Light W wind at the Pass.
Sunday
Night
Partly cloudy, then becoming mostly clear overnight. Light W wind at the Pass.
Sunday
Mostly cloudy with isolated rain or snow showers in the afternoon.
Sunday
Night
Partly cloudy early, then becoming mostly clear.
Sunday
A chance of very light rain or snow showers near the Cascade Crest.
Sunday
Night
A few clouds early, then becoming mostly clear.
Sunday
A chance of very light rain or snow showers near the Cascade Crest.
Sunday
Night
Partly cloudy early, then becoming mostly clear.
Sunday
Increasing mid-level clouds with a chance of a light rain or snow shower in the afternoon.
Sunday
Night
Partly cloudy with isolated snow flurries early, then clearing skies.
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).