Generally cloudy skies, light to moderate winds, and a few showers will sum up the weather for most locations on Sunday. A disintegrating front is lifting northward this morning, bringing showers to the region near and south of I-90. Look for precipitation to slowly make its way further north and arrive at Mt Baker around lunchtime or early afternoon. Behind the front, showers should gradually taper for the Mt Hood and West/East South zones, and you may even see some sun breaks this afternoon.
Easterly winds continue to decrease along the Cascade Crest and through the Passes. Eventually, ridgeline winds should turn more SW-W this morning. With the loss of cool east flow, the west slopes of the range will warm. There may be just enough low-level E flow to keep temperatures cold at Stevens Pass, and potentially Snoqualmie Pass, through the afternoon.
Any lingering showers quickly taper during the evening as a drier air mass traverses the area from S to N. Our next system arrives at Mt Hood around midnight as we set up for a rinse and repeat of today's weather. The only real difference between Sunday and Monday's storms is the depleted cold air pool east of the Cascades. Even as we return to stronger easterly winds, this time it won't have the same cooling effect. Snow levels rise to around 3500 to 4500 ft.
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 with some sun breaks possible in the afternoon. Light showers mainly in the southern and eastern Olympics.
Sunday
Night
Partly to mostly cloudy. A few isolated showers possible.
Sunday
Cloud. Light showers mainly in the afternoon. SSW winds becoming light to moderate.
Sunday
Night
Mostly cloudy with a few isolated showers, then clearing.
Sunday
Cloudy with light showers mainly in the afternoon.
Sunday
Night
Cloudy with a few isolated showers possible, then clearing. Winds turning SE and becoming light to moderate.
Sunday
Cloudy with light showers mainly in the morning. Slightly heavier on the volcanoes. A few sun breaks possible in the afternoon, primarily near the crest. SW winds becoming light to moderate.
Sunday
Night
Partly to mostly cloudy with a few showers lingering near the volcanoes. Clouds increasing towards daybreak. Winds turning SE and becoming moderate.
Sunday
Cloudy with occasional light snow showers. Light E flow at pass level gradually decreasing. Ridgeline winds turning from SE to SW.
Sunday
Night
Mostly cloudy with periods of mostly clear skies. A few flurries possible. Light E flow at pass level. Ridgeline winds turning SE and becoming light to moderate.
Sunday
Cloudy with a few light showers. Mostly snow at pass level but a chance of rain in the afternoon. Light E flow decreasing slightly. Ridgeline winds are a mix of light to moderate SE and SW.
Sunday
Night
Clearing in the evening with the chance for a few flurries. Then increasing clouds towards dawn. Light E flow at Pass level. Ridgeline winds turning SE and becoming moderate.
Sunday
Mostly cloudy with clouds lowering mid-day. Occasional light snow showers.
Sunday
Night
Mostly cloudy with a few stray showers possible.
Sunday
Cloudy with occasional light snow showers. A few sun breaks possible in the afternoon particularly south of the Wenatchee Mts. Winds becoming W light to moderate.
Sunday
Night
Partly to mostly cloudy with periods of clearer skies. A few flurries possible. Winds turning SSE and becoming light to moderate.
Sunday
Cloudy with light snow showers mainly in the morning. Some sun breaks in the afternoon. WSW wind turning W and becoming moderate.
Sunday
Night
Partly clear becoming cloudy overnight. Light showers developing after midnight. Winds becoming moderate from the SE.
Sunday
Cloudy with light to moderate showers mainly in the morning. Significant sun breaks in the afternoon. Moderate to strong W winds decreasing slightly.
Sunday
Night
Clouds increasing overnight with showers arriving around midnight. SSE winds becoming moderate.
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).