It's a different day but same upper level trough and general low pressure circulation off the south WA coast continues to rotate snow showers inland, mainly affecting areas from Snoqualmie Pass and south to Mt Hood with light but persistent snow showers. A few additional fluffy inches of snow can be expected in these areas today. Along the north slopes of the Olympics, cold Fraser outflow and ENE winds are leading to very localized banding of more moderate snow showers in that area.
The upper trough will pass inland during the day today with showers becoming more scattered in the afternoon. Skies will remain generally cloudy except for some partial clearing in the north Cascades and Olympics. Following a cold day, another cold night is on tap in the mountains, with widespread single-digit mountain temperatures forecast overnight.
High clouds ahead of the next frontal system will begin to roll in early Friday morning from the west. A slow moving low pressure system will stay well offshore and actually drop south along the coastline during the day. An occluded front should push inland Friday afternoon, reaching the Olympic peninsula, but the Cascades will likely have to wait until Friday night to see snow. With strong surface high pressure over southern B.C. and the low pressure offshore, expect offshore easterly winds to start to crank up during the day Friday and strengthen Friday night.
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
Mostly cloudy with scattered light snow showers, except locally moderate along the north slopes of the Olympics in the morning.
Thursday
Night
Cloudy.
Thursday
Cloudy with isolated snow showers, becoming partly to mostly cloudy in the afternoon.
Thursday
Night
Partly to mostly cloudy with high clouds increasing in the evening, then becoming cloudy.
Thursday
Cloudy with scattered light snow showers.
Thursday
Night
Partly to mostly cloudy with high clouds increasing in the evening, then becoming cloudy.
Thursday
Light to occasionally moderate snow showers in the morning, then light scattered snow showers in the afternoon.
Thursday
Night
Mostly cloudy with high clouds increasing in the evening, then becoming cloudy.
Thursday
Light snow showers in the morning, then light scattered snow showers in the afternoon. Variable light Pass level winds.
Thursday
Night
Mostly cloudy with high clouds increasing in the evening, then becoming cloudy. Light east winds at Pass level.
Thursday
Light to occasionally moderate snow showers in the morning, then light scattered snow showers in the afternoon. Variable light Pass level winds.
Thursday
Night
Mostly cloudy with high clouds increasing in the evening, then becoming cloudy. Light east winds at Pass level.
Thursday
Cloudy with scattered light snow showers.
Thursday
Night
Partly to mostly clear with high clouds increasing late.
Thursday
Light to occasionally moderate snow showers in the morning, heaviest near the Cascade crest, then light scattered snow showers in the afternoon.
Thursday
Night
Partly to mostly clear with high clouds increasing late.
Thursday
Light to occasionally moderate snow showers in the morning, heaviest near the Cascade crest, then light scattered snow showers in the afternoon.
Thursday
Night
Partly to mostly clear with high clouds increasing late.
Thursday
Light to occasionally moderate snow showers in the morning, then light scattered snow showers in the afternoon. Moderate to strong ridgeline winds.
Thursday
Night
Partly to mostly cloudy with isolated snow showers, mainly in the evening. 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).