We're in for an increasingly wet, windy, and mild weekend as an early Spring atmospheric river takes aim at the PNW. A weak warm front is already moving into the Olympics and northwest Cascades this morning with increasing precipitation rates in the afternoon. Precipitation will also spread south in the afternoon to the south Washington Cascades but will miss the Mt Hood area and the east slopes of the Cascades near and south of Hwy 12. After a cool start on Saturday morning, snow levels will rise to 6000' in the south and 3500-4500' in the north.
We may see a short breather Saturday evening before the bulk of the moisture begins to shift inland Sunday morning. Heavy precipitation is expected for the Olympics and northwest Cascades, including the Mt Baker area, during the day on Sunday. Moderate rain and snow will develop for the mountains further south and east during the day as well as strong S-SW winds in all areas. Snow levels will hold steady or rise slightly Saturday night, and then creep up further during the day on Sunday. We can expect rain at all lower elevation trailheads and a switch from snow to rain at mid-elevations. The slightly cooler north Cascades should hold a snow line around 4500-5500' Sunday afternoon, with snow levels soaring above 8000' down near Mt Hood.
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
Light rain and snow becoming light to moderate in the afternoon. Heaviest precipitation southern slopes of the Olympics. Strong ridgeline winds.
Saturday
Night
Light to occasionally moderate rain and snow increasing after midnight. Strong ridgeline winds.
Saturday
Light rain and snow becoming moderate in the afternoon. Strong ridgeline winds easing somewhat in the afternoon.
Saturday
Night
Light to occasionally moderate rain and snow increasing after midnight. Strong ridgeline winds.
Saturday
Light rain and snow becoming light to moderate in the afternoon. Moderate to strong ridgeline winds easing in the afternoon.
Saturday
Night
Light to occasionally moderate rain and snow increasing after midnight. Strong ridgeline winds.
Saturday
Cloudy in the morning with a chance of light rain or snow, then light rain and snow in the afternoon. Moderate ridgeline winds.
Saturday
Night
Cloudy with periods of light rain or snow increasing after midnight. Moderate ridgeline winds increasing to strong after midnight.
Saturday
Cloudy in the morning with a chance of light rain or snow, then light rain and snow in the afternoon. Moderate ridgeline W winds. Light east winds at Pass level.
Saturday
Night
Cloudy with periods of light rain or snow increasing after midnight. Moderate ridgeline W winds. Light east winds at Pass level.
Saturday
Cloudy in the morning with a chance of light rain or snow, then light rain and snow in the afternoon. Moderate ridgeline W winds. Light east winds at Pass level.
Saturday
Night
Cloudy with periods of light rain or snow increasing after midnight. Moderate ridgeline W winds. Light east winds at Pass level.
Saturday
Cloudy in the morning with a chance of light rain or snow, then light rain and snow in the afternoon. Moderate ridgeline winds.
Saturday
Night
Cloudy with light rain or snow increasing after midnight. Moderate ridgeline winds.
Saturday
Mostly cloudy in the morning, becoming cloudy mid-day. Light rain and snow developing in the afternoon. Moderate ridgeline winds.
Saturday
Night
Cloudy with periods of light rain or snow. Moderate ridgeline winds.
Saturday
Partly sunny to mostly cloudy in the morning, becoming cloudy in the afternoon. Chance of light rain or snow in the afternoon. Moderate ridgeline winds.
Saturday
Night
Cloudy with periods of light rain or snow. Moderate ridgeline winds.
Saturday
Partly sunny to mostly cloudy in the morning, becoming cloudy in the afternoon. Chance of light rain or snow in the afternoon. Strong ridgeline winds easing somewhat in the afternoon.
Saturday
Night
Cloudy with periods of light rain or snow. Strong 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).