A deep offshore trough and associated upper low will keep a consistent supply of moisture aimed at the Pacific Northwest. A slowing frontal boundary will stall over western Washington today. The front brought 3-4" of snow to the volcanoes as of 6 AM along with moderate sustained winds near and above treeline. The cyclonic nature of the flow pattern translates to SW flow over southern parts of our forecast area and SSW or S flow further north.
Periods of light to moderate snow will continue to favor the volcanoes today and tonight with precipitation. Snow levels will very gradually start to rise. Winds should decrease slightly but will likely remain in the moderate range for locations exposed to the SSW flow. E winds at the passes should gradually increase into the light to moderate range, peaking Sunday morning as a second front approaches. This next front should spread increased (moderate) rain and snow into the Olympics late Saturday night which should result in increased light to moderate snow in the Cascades on Sunday. Moderate winds will also become more widespread. Snow levels west of the Cascade Crest will rise above Snoqualmie Pass level, but despite warming E of the Cascade Crest, there is likely to be just enough cold air to keep the Pass all snow until late in the day. However, snow amounts through the passes should be light.
Expect 12-18" of snow at Mt. Baker with closer to 12" at Paradise and Mt. Hood through the end of the day on Sunday.
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
Periods of light snow mainly in the morning. Clouds thinning or frequent sun breaks in the afternoon.
Saturday
Night
Periods of increasing light snow.
Saturday
Moderate snow, heaviest in the afternoon.
Saturday
Night
Decreasing moderate snow.
Saturday
Periods of light snow, increasing in the afternoon.
Saturday
Night
Decreasing light snow.
Saturday
Light to moderate snow, heaviest at Mt St Helens, then Paradise.
Saturday
Night
Light to occasionally moderate snow, heaviest at Mt. St Helens, then Paradise.
Saturday
Periods of light snow. Increasing light E winds at the Pass.
Saturday
Night
Periods of light snow. Increasing light to occasionally moderate E winds at the Pass.
Saturday
Periods of light snow. Increasing light E winds at the Pass.
Saturday
Night
Periods of light snow. Light to moderate E winds at the Pass.
Saturday
Periods of increasing light snow.
Saturday
Night
Periods of light snow decreasing after midnight.
Saturday
Periods of light snow.
Saturday
Night
Periods of decreasing light snow.
Saturday
Periods of light snow.
Saturday
Night
Periods of decreasing light snow.
Saturday
Periods of light to moderate snow. Strong wind gusts above treeline.
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).