The remnants of a northward-moving upper low off the Pacific Northwest coastline will bring light to moderate precipitation across the region on Tuesday. One band of precipitation is weakening as it moves northward through the central Cascades and may fizzle before reaching Mt Baker. A second and more significant band of precipitation currently brings moderate precipitation to Mt Hood and the southern Cascade volcanoes. This should continue to lift northward and bring a wind shift from S to SW, ushering additional warming in its wake.
The situation gets complicated when we add in easterly low-level flow. There's enough cold air that the mountain passes have been receiving light snowfall this morning. Snow should continue through around 10 AM, but warming as the precipitation trails off from late morning through the afternoon hour should transition the major central Cascade Passes from snow to rain or freezing rain as warmth overwhelms the cold air at middle elevations. Washington Pass should remain all snow. Snow levels west of the Cascade Crest should be around 5500-6500 ft on Tuesday.
Precipitation tapers from south to north, with some moderate precipitation lingering for Mt Baker through the evening hours.
On Wednesday, a cutoff low moves into position off the California Coast and the main jetstream remains to our north. Therefore, expect mostly sunny skies with light winds aloft and increasing light to moderate E flow through the mountain gaps.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
Use dropdown to select your zone
Tuesday
Periods of light rain and higher elevation snow focusing on the southern Olympics. Light to occasionally moderate ridgeline winds.
Tuesday
Night
A few scattered rain or snow showers in the evening for the SW slopes of the Olympics, then becoming mostly to partly cloudy.
Tuesday
Cloudy early, then periods of light to moderate rain and high-elevation snow from mid-morning onwards. Light to moderate ridgeline winds.
Tuesday
Night
Decreasing light rain or high-elevation snow showers. Light to moderate ridgeline winds.
Tuesday
Periods of light to moderate rain and high-elevation snow. Mostly light ridgeline winds.
Tuesday
Night
Decreasing very light rain or high elevation snow showers in the early evening, then mostly cloudy. Light ridgeline winds.
Tuesday
Periods of light to moderate rain and high-elevation snow are heaviest on the volcanoes and through the morning hours. Lower snow levels near the mountain gaps. Mostly light ridgeline winds.
Tuesday
Night
A chance of a light rain or high-elevation snow shower in the early evening, then gradually decreasing clouds. Light ridgeline winds.
Tuesday
Periods of light snow changing to rain or freezing rain late in the day. Light ridgeline winds. Decreasing light E wind at the Pass.
Tuesday
Night
Periods of light rain or mixed precipitation decreasing or ending. Light ridgeline and E wind at the Pass.
Tuesday
Periods of light snow changing to rain or freezing rain during the mid-day hours. Moderate ridgeline winds. Decreasing light to moderate E wind at the Pass.
Tuesday
Night
Periods of light rain decreasing or ending. Light ridgeline and E wind at the Pass.
Tuesday
Periods of light snow. Mostly light ridgeline winds.
Tuesday
Night
Decreasing light snow. Light ridgeline winds.
Tuesday
Periods of light snow in the morning may mix with freezing rain or rain in the afternoon. Increasing light to moderate ridgeline winds.
Tuesday
Night
Light rain or snow showers in the early evening, then gradually decreasing clouds. Decreasing light to occasionally moderate ridgeline winds.
Tuesday
Periods of light snow in the morning mixing with and changing over to freezing rain or rain in the late morning hours. Increasing 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).