A front passed through the Cascades early Saturday morning. Vigorous rain and snow showers continue in its wake. Moderate to locally strong WSW winds switching W in the afternoon will make these showers feel more like steady precipitation with fluctuating intensity over the mountains. Expect slightly above average temperatures with snow levels bumping up to 3500-4000 ft as cooler air east of the Cascades gets scoured out. Already Stevens and Snoqualmie Passes have transitioned to rain. The winds will continue through the end of the day and will be most impactful near and east of the Cascade Crest.
Rain and snow showers taper Saturday evening. Attention focuses on the next system as low forming off the mouth of the Columbia lifts a moisture-laden warm front to the Washington-Oregon border. This front spreads moderate to heavy rain and snow into areas south of I-90 and light to moderate rain and snow into the central Cascades on Sunday. This system with E flow and a trough moving in from the north should lower snow levels into the 2500-3500 ft range. Steadier snowfall becomes showery late in the afternoon with moderate to strong W winds rapidly increasing over the southern Cascades late in the day as the trough works southward.
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
Decreasing rain and snow showers. Moderate ridgeline winds.
Saturday
Night
Saturday
Heavy rain and snow becoming increasingly showery. Decreasing moderate ridgeline winds with strong gusts.
Saturday
Night
Saturday
Heavy rain and snow becoming increasingly showery. Moderate ridgeline winds with strong gusts.
Saturday
Night
Saturday
Heavy rain and snow becoming increasingly showery (moderate at Crystal and White Pass). Moderate ridgeline winds with strong gusts.
Saturday
Night
Saturday
Moderate to occasionally heavy rain and snow becoming increasingly showery. Moderate to occasionally strong ridgeline winds. Light to occasionally moderate W wind at the Pass.
Saturday
Night
Decreasing light rain and snow showers. Moderate ridgeline winds become light. Light W wind at the pass switches E.
Saturday
Moderate to occasionally heavy rain and snow becoming increasingly showery. Moderate to occasionally strong ridgeline winds. Light to occasionally moderate W wind at the Pass.
Saturday
Night
Decreasing light rain and snow showers. Moderate ridgeline winds become light. Light W wind at the pass switches E.
Saturday
Moderate rain and snow showers. Moderate ridgeline winds.
Saturday
Night
Decreasing rain and snow showers mainly near the Cascade Crest. Decreasing moderate ridgeline winds become light.
Saturday
Moderate rain and snow showers. Moderate ridgeline winds become locally strong.
Saturday
Night
Decreasing rain and snow showers mainly near the Cascade Crest. Decreasing moderate ridgeline winds become light.
Saturday
Moderate rain and snow showers. Moderate ridgeline winds become locally strong.
Saturday
Night
A few rain and snow showers in the evening, then light snow develops overnight. Moderate ridgeline winds become light.
Saturday
Moderate rain and snow showers. Moderate ridgeline winds become locally strong.
Saturday
Night
Light snow showers early, then light to moderate rain and snow develop overnight. Moderate ridgeline winds become light.
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).