The last weather system in a brief multi-day interlude of wet weather will cross the Pacific Northwest today before we dry out once again. While this system will start with some snowflakes between 3000-4000', a warming trend will turn snow to rain at Pass levels and mid-elevations this afternoon outside of the north Cascades, where snow levels will stay slightly cooler. The period between late morning and early afternoon is expected to feature moderate precipitation, with rates gradually decreasing in the late afternoon and into the evening. Look for snow levels to jump to 4500-5500' for the central/south WA Cascades in the afternoon. It will be milder and drier further south near Mt. Hood.
Strong upper level ridging will build along the west coast later today into Monday night. Drippy weather will continue along the west slopes of the Cascades this evening, but with drier air moving in, we should be done with the drippiness before sunrise on Tuesday. Freezing levels will shoot up to 9000' on Tuesday, but we won't be totally in the clear yet. Low-level clouds should take a while to break up on Tuesday, if at all, near the Passes and along portions of the east slopes of the Cascades. A weather system well to our north will bring some high and mid clouds over the Olympics and north Cascades. The south WA Cascades and Mt Hood will see the most sunshine in this pattern.
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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Monday
Light to moderate rain and snow. Moderate ridgeline winds.
Monday
Night
Light rain or snow in the evening, then cloudy. Light to moderate ridgeline winds.
Monday
Light to moderate rain and snow. Moderate ridgeline winds.
Monday
Night
Light rain or snow in the evening, then cloudy.Light to moderate ridgeline winds.
Monday
Light to moderate rain and snow. Moderate ridgeline winds.
Monday
Night
Light rain or snow in the evening, then cloudy. Light to moderate ridgeline winds.
Monday
Light to moderate rain and snow, easing late afternoon. Moderate to strong ridgeline winds.
Monday
Night
Light rain or snow in the evening, then mostly to partly cloudy. Light to moderate ridgeline winds.
Monday
Light to moderate rain and snow. Light E winds at Pass level. Moderate W ridgeline winds.
Monday
Night
Light rain or snow in the evening, then cloudy. Light E winds at Pass level. Light to moderate W ridgeline winds.
Monday
Light to moderate rain and snow. Light E winds at Pass level. Moderate W ridgeline winds.
Monday
Night
Light rain or snow in the evening, then cloudy. Light to moderate W ridgeline winds.
Monday
Light rain and snow, developing and becoming occasionally moderate near the Cascade crest. Moderate ridgeline winds.
Monday
Night
Periods of light rain or snow in the evening, then mostly cloudy. Light to moderate ridgeline winds.
Monday
Light rain and snow, developing and becoming occasionally moderate near the Cascade crest. Moderate ridgeline winds.
Monday
Night
Light rain or snow in the evening, then partly to mostly cloudy. Light to moderate ridgeline winds.
Monday
Light rain and snow, developing and becoming occasionally moderate near the Cascade crest through early afternoon. Moderate ridgeline winds.
Monday
Night
Light rain or snow in the evening, then partly cloudy. Light to moderate ridgeline winds.
Monday
Partly to mostly cloudy with a chance of rain or snow mid-day. Moderate to strong ridgeline winds.
Monday
Night
Partly to mostly clear. Light to moderate 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).