One last day of generally quiet, mild, and dry weather before a storm arrives tomorrow morning. A system passing to our north will drag clouds over the region today. Locations north of about US Hwy 2 should see cloudy to mostly cloudy skies, with a bit more sunshine further south and east. While most precipitation will stay north of the border, you might encounter a stray shower in the North Cascades.
As we head into the afternoon and evening, conditions will change. Winds turn more southerly and start to increase substantially. Many areas will see moderate to strong and gust S to SW winds overnight.
Precipitation should arrive in the Olympics and Baker areas in the dark early morning hours before quickly spreading south and east. With warm air in place, many sites will initially see rain, but a strong cold front should cause snow levels to fall by mid-morning. This fast-moving storm brings a compact band of moderate precipitation and strong winds to the mountains during the day. Easterly flow in the Passes will help lower the snow levels, but a shift to westerly winds could cause a brief return to rain at pass level for Snoqualmie and perhaps Stevens.
By late afternoon, winds turn more westerly, and snowfall rates should start to taper. However, with plenty of moisture in place, westerly winds and a Puget Sound Convergence Zone should help showers add to the snow totals.
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. A few isolated sprinkles possible.
Thursday
Night
Cloudy with increasing significantly. Becoming SW moderate to strong. Showers possible after midnight.
Thursday
Mostly cloudy with moderate SSW winds increaing in the afternoon. A few isolated showers possible.
Thursday
Night
Cloudy. Moderate S winds becoming strong and gusty. A few showers possible after midnight.
Thursday
Mostly cloudy. Light to moderate SW winds.
Thursday
Night
Cloudy. Light to moderate S winds increasing.
Thursday
Partly cloudy. Light SW winds.
Thursday
Night
Becoming cloudy. Winds increasing and becoming moderate SSW.
Thursday
Partly to mostly cloudy. Light E flow with some low clouds possible particularly E of the Pass.
Thursday
Night
Cloudy. Light E flow. Ridgeline winds becoming S light to moderate.
Thursday
Partly cloudy. Light E flow could bring low clouds/fog into the Pass.
Thursday
Night
Cloudy. Light E flow. Ridgeline winds becoming S moderate.
Thursday
Mostly cloudy with valley fog. A few sprinkles possible near the Canadian border. Light to moderate WSW winds.
Thursday
Night
Cloudy. SW winds becoming moderate.
Thursday
Partly to mostly cloudy with valley fog. Light to moderate westerly winds.
Thursday
Night
Cloudy with increasing winds. Becoming SW moderate to strong and gusty.
Thursday
Partly cloudy with some valley fog.
Thursday
Night
Becoming cloudy. SW winds increasing significantly from moderate to strong and gusty.
Thursday
Partly cloudy with some low clouds/fog. Winds becoming SW light to moderate.
Thursday
Night
Becoming cloudy. Winds increasing significantly with very strong and gusty alpine winds. Ridgeline winds also becoming strong and gusty.
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).