A compact band of precipitation will rotate through the region this morning bringing a few hours of moderate rain and high elevation snow to the mountains. The bulk of the precipitation should focus on the southern volcanoes with locations near Mt Hood and Mt St Helens set to see the highest totals. While most areas will experience dry conditions by the afternoon hours, rain and snow could linger for sites near the Washington-Oregon border into the evening. Moderate to strong SW winds associated with this weakening front will very quickly decrease and turn more northerly as the parent low-pressure shifts inland during the day.
A high-pressure ridge will build into the Pacific Northwest overnight and help the mountains dry out. You may find weak inversions in the valleys and passes leading to low-level clouds and fog that could persist into the morning. Friday should be a mostly sunny and dry day. Warmer air will push into the region under the ridge sending our freezing levels on a steady march upward. This will continue an extended period of warm weather that began this past Tuesday and should at least last through the weekend.
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
Periods of moderate rain and snow in the morning. Heaviest in the southern and western Olympics. Drying in the afternoon.
Thursday
Night
Mostly clear with valley fog. Warming.
Thursday
A brief period of rain and snow in the morning. Moderate S winds quickly decreasing and becoming northerly.
Thursday
Night
Mostly clear with some low clouds and fog. Winds becoming S overnight and increasing.
Thursday
A brief period of rain and snow in the morning. Moderate SSW winds quickly decreasing.
Thursday
Night
Mostly clear with some low clouds and valley fog.
Thursday
Rain and snow, mainly in the morning. Heaviest near Mt St Helens and Mt Adams. Moderate SSW winds quickly decreasing.
Thursday
Night
Partly cloudy. Scattered showers possible near Mt St Helens and Mt Adams. Low clouds and fog possible further north.
Thursday
A brief period of rain and snow in the morning. Weak E flow at Pass level decreasing.
Thursday
Night
Mostly clear with low clouds and fog. Weak inversion at Pass level. E flow returning overnight.
Thursday
Rain and snow mainly in the morning. E flow at Pass level becoming W.
Thursday
Night
Mostly clear. Weak inversion at Pass level. Low clouds and fog. E flow returning overnight.
Thursday
Mostly cloudy with scattered showers in the morning. More sunshine possible in the afternoon.
Thursday
Night
Mostly clear with light winds.
Thursday
Cloudy with scattered showers in the morning. Moderate SW winds quickly decreasing. Some clearing in the afternoon.
Thursday
Night
Mostly clear with low clouds and valley fog particularly closer to the Cascade crest.
Thursday
Cloudy with showers in the morning. Moderate SW winds decreasing.
Thursday
Night
Partly to mostly clear. Patchy fog possible further north in the zone.
Thursday
Moderate rain and snow throughout the day. Strong SW winds becoming W.
Thursday
Night
Rain and snow showers in the evening, ending overnight with some drying. Warming.
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).