A fast moving frontal system will deliver a round of heavy precipitation predominantly to the west slopes of the Washington Cascades this morning before becoming more showery mid-day through this afternoon. While the heaviest precipitation will be focused on the west slopes, all areas will see strong west winds, and in some locations, extreme winds. Unfortunately, snow levels are starting quite high, but the good news is on the way as snow levels slowly lower during the day, and then fall rapidly to near sea-level late tonight through Monday.
A Puget Sound convergence zone will take shape later this morning and focus additional moisture into the Mtn Loop and Stevens Pass areas this afternoon through tonight. Once snow levels fall below Pass level this afternoon/evening, we'll start to stack up several inches of low-density snow that could total over a 1' for areas closest to the convergence zone bulleyes Sunday night through Monday afternoon.
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
Light to moderate rain and snow showers this morning, becoming partly sunny with isolated light rain and snow showers this afternoon. Moderate to strong ridgeline winds.
Sunday
Night
Light to occasionally moderate snow showers. Moderate to strong ridgeline winds.
Sunday
Moderate to occasionally heavy rain and snow this morning, becoming partly to mostly cloudy with scattered light rain and snow showers this afternoon. Moderate to strong ridgeline winds.
Sunday
Night
Light to occasionally moderate snow showers. Moderate to strong ridgeline winds.
Sunday
Moderate to occasionally heavy rain and snow this morning, becoming light to moderate rain and snow showers this afternoon. Moderate to strong ridgeline winds.
Sunday
Night
Light to moderate snow showers, occasionally heavy near convergence zone. Moderate to strong ridgeline winds.
Sunday
Light to moderate rain and snow this morning, becoming light to occasionally moderate rain and snow showers this afternoon. Moderate to strong ridgeline winds.
Sunday
Night
Light to occasionally moderate snow showers. Moderate to strong ridgeline winds.
Sunday
Moderate to occasionally heavy rain and snow this morning, becoming light to moderate rain and snow showers this afternoon. Moderate W Pass level winds, strong at ridgeline.
Sunday
Night
Light to moderate snow showers, occasionally heavy near convergence zone. Moderate W Pass level winds, strong at ridgeline.
Sunday
Moderate to occasionally heavy rain and snow this morning, becoming light to moderate rain and snow showers this afternoon. Moderate W Pass level winds, strong at ridgeline.
Sunday
Night
Light to moderate snow showers. Moderate W Pass level winds, strong at ridgeline.
Sunday
Light rain and snow this morning, heaviest near the crest, becoming partly sunny with isolated light rain and snow showers this afternoon. Moderate to strong ridgeline winds.
Sunday
Night
Partly to mostly cloudy with scattered light snow showers, heavier west-side. Moderate to strong ridgeline winds.
Sunday
Light rain and snow this morning, heaviest near the crest, becoming partly sunny with isolated light rain and snow showers this afternoon. Strong to extreme ridgeline winds.
Sunday
Night
Partly to mostly cloudy with scattered light snow showers, heavier west-side. Strong to extreme ridgeline winds.
Sunday
Mostly cloudy with periods of light rain and snow this morning, becoming partly sunny to mostly cloudy with isolated light rain and snow showers this afternoon. Strong to extreme ridgeline winds.
Sunday
Night
Partly to mostly cloudy with scattered light snow showers, heavier west-side. Strong to extreme ridgeline winds.
Sunday
Mostly cloudy with periods of light rain and snow showers mainly west-side of the mountain, partly sunny with scattered showers east-side. Strong to extreme ridgeline winds.
Sunday
Night
Partly to mostly cloudy with scattered light snow showers, heavier west-side. Strong to extreme ridgeline 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).