A weak surface low dissipates as it tracks towards Vancouver Island Thursday morning. Out ahead of the associated front, a continuous band of light to occasionally moderate rain and snow has moved into the Olympics and Mt. Baker area this morning and should expand throughout the west slopes of the Washington Cascades by the afternoon. Expect slight spillover onto the east slopes of the Cascades. Light to moderate S winds Thursday morning should shift SW in the afternoon and WSW Thursday night as the fizzling front moves onshore. On Thursday, the southerly winds should favor Mt. Baker while the more westerly wind shift overnight favors a more equitable distribution of light shower activity. Snow levels should remain above Snoqualmie Pass level throughout the forecast period.
Rain and snow showers should be lighter on Friday with some lingering moisture that keeps the rain and snow showers alive. Winds shift more SWerly ahead of the next system as the extension of a warm front approaches.
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
Light rain and snow becoming showery in by late morning.
Thursday
Night
Partly cloudy.
Thursday
Increasing light to occasionally moderate rain and snow.
Thursday
Night
Light rain and snow showers.
Thursday
Mostly cloudy with light rain and snow from late morning onwards.
Thursday
Night
Decreasing light rain and snow showers.
Thursday
Cloudy in the morning with light rain and snow developing in the afternoon. Crystal mostly rain shadowed.
Thursday
Night
Decreasing light rain and snow showers. Crystal mostly rain shadowed.
Thursday
Cloudy in the morning with light rain and snow developing by the afternoon. Light E wind switching W at the Pass by late morning.
Thursday
Night
Decreasing light rain and snow showers. Light W wind at the Pass.
Thursday
Cloudy in the morning with light rain and snow developing by the afternoon. Light E wind switching W at the Pass by late morning.
Thursday
Night
Decreasing light rain and snow showers. Light W wind at the Pass.
Thursday
Cloudy in the morning with light rain and snow developing by the afternoon.
Thursday
Night
Decreasing light rain and snow showers.
Thursday
Cloudy in the morning with light rain and snow in the afternoon near the Cascade Crest.
Thursday
Night
Decreasing light rain and snow showers.
Thursday
Mostly cloudy with clouds lowering and thickening late in the day.
Thursday
Night
Light rain and snow showers.
Thursday
Mostly cloudy. Strong ridgeline wind gusts.
Thursday
Night
Light rain and snow showers. Strong ridgeline wind 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).