We're in for a warm, wet, and windy day across nearly all of the forecast areas on Saturday. A well defined N-S oriented band of precipitation has already arrived in the Olympics this morning. Rain and snow will spread inland, first to the Mt Baker area early this morning and then to the Central and Southern Cascades before lunchtime, and finally to Mt Hood in the early afternoon. Stormy conditions with periods of heavey precipitations and gusty winds are expected for the western Olympics, North Cascades, Snoqualmie Pass, and Mt Rainier areas. Unfortunately, temperatures are still very mild across the region. So, while this storm comes with a general cooling trend, snow levels will initially remain well above most trailhead locations.
The storm peaks in the afternoon and early evening, with precipitation easily spilling over the crest to locations further east. The bulk of the storm moves south and east of the area, with post-frontal showers focusing mainly near and west of the crest. For most locations, precipitation continues to taper overnight and finally ends before Sunday morning. The exception is Mt Hood, where the storm is just getting started. A short wave system arrives early Sunday morning, reinvigorating precipitation and lifting a band of heavier rain and snow northward from Oregon. Models disagree about how far this will reach into the Cascades, but the best chance of rain and snow seems to be from about I-90 southward. Cold air with this second storm should help snow levels fall further, closer to trailhead elevations.
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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Saturday
Stormy with rain and high elevation snow, heavy in the western Olympics. Strong and gusty SSW winds turning SW and decreasing.
Saturday
Night
Rain and snow showers with lowering snow levels. Light to moderate SW winds decreasing.
Saturday
Becoming stormy with heavy rain, high elevation snow, and strong and gusty SSW winds. Winds decrease slightly in the afternoon.
Saturday
Night
Rain and snow in the evening, becoming showery overnight with decreasing snow levels. Moderate SW winds turning W and decreasing.
Saturday
Cloudy in the morning, then becoming stormy before lunch. Periods of heavy rain, high elevation snow, and moderate to strong and gusty SSW winds. Winds decrease slightly in the evening.
Saturday
Night
Stormy in the evening with periods of heavy rain and snow. Becoming showery overnight. Moderate SW winds turning W and decreasing.
Saturday
Cloudy in the morning, with rain and high elevation snow developing late morning to near lunch time. Precipitation heaviest near Mt Rainier. Moderate to strong and gusty SW winds decreasing slightly in the afternoon.
Saturday
Night
Stormy in the evening with periods of moderate to heavy rain and snow with decreasing snow levels. Light to moderate WSW winds decreasing.
Saturday
Cloudy with rain and high elevation snow developing around lunchtime. Precipitation could be heavy at times in the afternoon. Light east flow at pass level. SW ridgeline winds light to moderate.
Saturday
Night
Rain and snow mainly in the evening with decreasing snow levels. Becoming showery overnight. Light to moderate ridgeline winds backing from SW to W.
Saturday
Cloudy in the morning with rain and snow developing between late morning and just before lunchtime. Precipitation could be heavy at times in the afternoon. Light easterly flow at pass level. Gusty moderate SW ridgeline winds becoming stronger in the afternoon.
Saturday
Night
Story in the evening with rain and snow, could be heavy at times. Light to moderate WSW winds turning W.
Saturday
Cloudy with rain and snow developing late morning. Precipitation heaviest in the afternoon near the crest. Gusty moderate SW winds.
Saturday
Night
Rain and snow in the evening, becoming showery. Light to moderate winds backing from SW to W.
Saturday
Cloudy with rain and high elevation snow developing around lunchtime. Precipitation heaviest in the afternoon near the Cascade Crest. Moderate to strong and gusty SW winds.
Saturday
Night
Rain and snow in the evening, becoming showery. Moderate to strong and gusty W winds decreasing slightly.
Saturday
Cloudy in the morning with rain and high elevation snow developing during the day. Moderate to strong and gusty SW winds.
Saturday
Night
Rain and snow in the evening, becoming more showery overnight. Gusty moderate W winds.
Saturday
Cloudy with rain and high elevation snow starting around lunchtime. Strong and gusty SW winds increasing in the afternoon.
Saturday
Night
Stormy with periods of heavy rain and snow. Snow levels dropping. Moderate to strong and gusty W winds decreasing significantly.
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).