Post-frontal rain and snow showers round an expanding offshore ridge on Thursday. These snow showers are mostly focused on areas near or west of the Cascade Crest, but expect some enhancement for the west slopes in convergence banding with some spillover to the east slopes in these areas. Convergence bands are mainly forming and reforming between Hwy 2 and Snoqualmie Pass, with locally moderate intensity possible at times. Most other showers should be light. Snow levels start the day around 3000 ft and remain relatively steady, but could bump up slightly to 3500 ft in some areas with daytime warming. Moderate to locally strong ridgeline winds will focus on the southern Cascades, particularly near and east of the Cascade Crest and Mt Hood. These winds should gradually decrease during the day.
A lull between disturbances decreases rain/snow shower activity Thursday night, with snow levels staying relatively steady and ridgeline winds becoming mostly light.
Another disturbance approaches on Friday, with rain and snow increasing late Thursday night and peaking in the light-to-moderate range Friday morning as a warm front approaches. This precipitation appears to be stratiform and steady, becoming more showery in the afternoon.
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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Thursday
Occasional light rain or snow showers.
Thursday
Night
Increasing light rain and snow showers.
Thursday
Decreasing light rain and snow showers.
Thursday
Night
Increasing light rain and snow showers.
Thursday
Decreasing light rain and snow showers with weak convergence at times.
Thursday
Night
Increasing light rain and snow showers.
Thursday
Occasional light rain and snow showers. Moderate ridgeline winds near the Cascade Crest.
Thursday
Night
Increasing light rain and snow showers.
Thursday
Decreasing light rain and snow showers with weak convergence at times. Light to moderate ridgeline and light W wind at the Pass.
Thursday
Night
Increasing light rain and snow showers. Mostly light ridgeline and light W wind at the Pass.
Thursday
Decreasing light rain and snow showers with weak convergence at times. Light to moderate ridgeline and W wind at the Pass.
Thursday
Night
Increasing light rain and snow showers. Mostly light ridgeline and light W wind at the Pass.
Thursday
Mostly cloudy in the morning, then partly cloudy in the afternoon. Isolated snow showers near the Cascade Crest.
Thursday
Night
Increasing light rain and snow showers. Light to moderate ridgeline and light W wind at the Pass.
Thursday
Rain and snow showers with convergence spillover near the Cascade Crest. Partly cloudy further east.
Thursday
Night
Very light rain or snow showers at times. Moderate ridgeline winds.
Thursday
Rain and snow showers with convergence spillover near the Cascade Crest. Partly cloudy further east. Moderate ridgeline winds.
Thursday
Night
Very light rain or snow showers at times. Moderate ridgeline winds.
Thursday
Light snow showers, mainly on the west side of the mountain. Mostly sunny further east. Decreasing strong to extreme ridgeline winds.
Thursday
Night
Increasing light snow showers. Moderate ridgeline winds with strong gusts.
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).