Active weather continues through the weekend. An upper low sitting over Washington State provides the instability for isolated bands of shower activity with upper-level WSW to SSW winds ahead of the next system guiding these showers. As the day progresses, these showers will be replaced by steadier and increasing light to moderate rain and snow. Snow levels dropped to around 4000 ft at the coast and 2500 ft near and west of the Cascade Crest Friday night, equilibrating temperatures relative to the east slopes of the Cascades. Temperatures should gradually rise as the next system arrives with moderate ridgeline winds peaking ahead of a frontal passage in the 2-5 AM time frame Sunday morning. With marginal temperatures at Snoqualmie Pass, don't expect significant accumulations until you get above 4000 ft. However, E flow could result in fluctuating snow levels and a slight chance of freezing rain at Pass level. Mt Baker has a favorable flow pattern, but some models have backed off on water numbers, so there's some uncertainty in rain/snow intensity.
Mostly light post-frontal rain and snow showers will continue on Sunday, focusing more on the northern and central Washington Cascades and gradually easing during the afternoon. Expect storm total water numbers in the 0.5-1.5" range, with the highest amounts at Paradise. This should translate into 6-15" of snow above 3500-4000 ft.
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
Mostly cloudy in the morning with light rain and snow showers developing in the afternoon. Moderate ridgeline winds late in the day.
Saturday
Night
Moderate rain and snow becomes light and showery overnight. Decreasing moderate ridgeline winds.
Saturday
Partly to mostly cloudy with a few rain or snow showers in the morning. Light rain or snow develops late in the day. Increasing light to moderate ridgeline winds.
Saturday
Night
Increasing moderate to heavy rain and snow. Moderate ridgeline winds with strong gusts.
Saturday
Partly to mostly cloudy with a few rain or snow showers in the morning. Light rain or snow develops late in the day. Increasing light to moderate ridgeline winds.
Saturday
Night
Increasing moderate rain and snow may become heavy. Increasing moderate ridgeline winds.
Saturday
Light rain and snow showers transition to increasing light to moderate rain and snow. Increasing light to moderate ridgeline winds.
Saturday
Night
Heavy rain and snow at Paradise. Moderate rain and snow at Crystal and White Pass. Increasing moderate ridgeline winds.
Saturday
Partly to mostly cloudy in the morning with a few rain and snow showers, then light rain and snow developing by the end of the day. Light ridgeline (WSW) and E wind at the Pass.
Saturday
Night
Moderate rain and snow. Light and shifting ridgeline winds. Light E wind at the Pass.
Saturday
Partly to mostly cloudy in the morning with a few rain and snow showers, then light rain and snow developing by the end of the day. Light ridgeline (WSW) and E wind at the Pass.
Saturday
Night
Moderate to heavy rain and snow with a slight chance of freezing rain. Snow levels generally near or slightly above the Pass. Light and shifting ridgeline winds. Light E wind at the Pass.
Saturday
Partly cloudy with clouds increasing and isolated rain and snow showers, mainly in the afternoon.
Saturday
Night
Increasing light to moderate rain and snow.
Saturday
Partly cloudy with clouds increasing and isolated rain and snow showers, mainly in the afternoon.
Saturday
Night
Increasing moderate rain and snow. Increasing light to moderate ridgeline winds.
Saturday
Partly cloudy with clouds increasing and isolated rain and snow showers, mainly in the afternoon.
Saturday
Night
Moderate rain and snow. Increasing light to moderate ridgeline winds.
Saturday
Light rain and snow showers in the morning, becoming moderate rain and snow by mid-afternoon. Moderate ridgeline winds increase and potentially become strong at times late in the day.
Saturday
Night
Moderate to heavy rain and snow along with fluctuating snow levels. Increasing moderate to 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).