Our wet and windy pattern continues as the low pressure system in the eastern Pacific spins wave after wave of moisture into the Northwest. A warm front is already lifting northward through the region this morning, bringing rain and snow to the mountains. Moderate to strong E-SE winds continue to impact areas along the Cascade Crest and through the Passes. These easterly winds should gradually decrease in the afternoon as the main low pressure center weakens. The combination of SE low-level winds and a strong overhead jet stream helps carry showers to locations in the eastern forecast zones.
By the evening, most locations should see a relative break in the action as precipitation turns more showery. The lull doesn't seem to last long as yet another short wave system arrives around midnight. This time, strong SW winds provide a more 'normal' Cascade storm track. Precipitation ramps up first in the Olympics and Mt Baker areas before shifting south and east. With plenty of deep Pacific moisture and help from a strong jet stream, this storm should provide more significant precipitation than many of the recent systems we've experienced.
The focus of the storm drifts southward on Monday, eventually focusing a narrow band of heavier precipitation near Mt Saint Helens. Weather models seem to disagree about how fast rain and snow shut off further north, and exactly where this main axis of moisture will focus. Due to the concentrated nature of this feature, it could have a major impact on storm totals and how warm some locations become.
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
Stormy with strong and gusty winds and moderate precipitation. Rain and snow heaviest in the southern Olympics.
Sunday
Night
Stormy, moderate to strong, and gusty winds. Precipitation heaviest in the western Olympics.
Sunday
Rain and snow throughout the day, could be moderate to heavy at times. Moderate to strong and gusty SSE winds turning S.
Sunday
Night
Stormy with periods of heavy precipitation. Moderate but gusty S winds turning SSW and increasing.
Sunday
Rain and snow showers throughout the day. Moderate but gusty SE winds turning S.
Sunday
Night
Rain and snow increasing overnight, becoming heavy at times. Moderate and gusty S winds turning SW.
Sunday
Rain and snow showers throughout the day. Moderate to strong and gusty SE winds, particularly near the crest, decreasing in the afternoon.
Sunday
Night
Showers in the evening with rain and snow developing around midnight. Moderate S winds turning SW.
Sunday
Light flurries with occasional showers. Light to moderate SE winds turning S. Light to moderate east flow at Pass level decreasing in the afternoon.
Sunday
Night
A few showers in the evening, then rain and snow arriving overnight. Light to moderate S winds turning SW. Light east flow at Pass level, decreasing and eventually turning W.
Sunday
Light flurries with a few slightly heavier showers. Moderate SE winds turning SSE and decreasingin the afternoon. Moderate east flow at Pass level, decreasing through the day.
Sunday
Night
A few showers in the evening, then rain and snow arriving around midnight. Light to moderate SSE winds turning SW. Light E flow at Pass level gradually decreasing and eventually turning W.
Sunday
Cloudy with showers, mainly in the afternoon. Moderate SSE winds turning S and decreasing.
Sunday
Night
A few showers in the evening, then more consistent precipitation arriving in the early morning hours. Light to moderate SSE winds turning SSW.
Sunday
Cloudy with a few showers, mostly in the afternoon. Moderate S winds turning SW.
Sunday
Night
Cloudy with a few showers in the evening. More consistent precipitation arriving overnight. Moderate SSW winds turning SW and increasing.
Sunday
Cloudy with showers throughout the day. Moderate to strong and gusty SSE winds turning SW.
Sunday
Night
Showers in the evening, then more constant precipitation arriving overnight. Moderate SSW winds turning SW.
Sunday
Rain and snow showers throughout the day, increasing in the afternoon. Moderate to strong and gusty SSW winds turning SW.
Sunday
Night
Rain and snow, could be moderate to heavy at times. Strong and gusty SW winds.
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).