Convergence zone snow bands have finally petered out this morning after delivering a walloping of snow to the central Cascades, especially Snoqualmie and Stevens Pass. Scattered showers for the central and south Cascades and Mt Hood area will taper off later this morning with little new snow accumulations likely. Moderate to strong ridgeline winds in the same areas, especially Mt Hood will also decrease rapidly later this morning. As an upper level ridge builds offshore today, a clearing trend will begin in the afternoon. Low level moisture and clouds will stick around, resulting in a mix of sun and clouds for the west slopes of the Cascades and Olympics with sunnier conditions on the east-side of Mt Hood and the east slopes of the Cascades.
An incoming frontal system will spread high clouds over the area tonight as offshore flow and easterly winds increase through the Cascade gaps. The front will begin to wash out as it approaches the coast on Thursday. Light precipitation should spread over inland by late morning for most areas. Slightly better dynamics will support more precipitation for the south Washington Cascades and Mt Hood on Thursday afternoon. Southerly winds will begin to increase in many areas Thursday afternoon as well.
A trailing upper level and surface trough Thursday night will help reinvigorate shower activity across the area with a frontal passage likely after midnight.
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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Wednesday
Mostly sunny this morning becoming partly sunny in the afternoon.
Wednesday
Night
Increasing high clouds, becoming overcast before midnight.
Wednesday
Mostly cloudy with isolated light rain and snow showers this morning becoming partly to mostly sunny this afternoon.
Wednesday
Night
Increasing high clouds in the evening, becoming overcast after midnight.
Wednesday
Mostly cloudy with scattered light rain and snow showers this morning becoming partly sunny this afternoon.
Wednesday
Night
Increasing high clouds in the evening, becoming overcast after midnight.
Wednesday
Mostly cloudy with scattered light rain and snow showers this morning becoming partly sunny this afternoon.
Wednesday
Night
Increasing high clouds in the evening, becoming overcast after midnight.
Wednesday
Mostly cloudy with scattered light rain and snow showers this morning becoming partly sunny this afternoon. Light to moderate west winds at Pass level.
Wednesday
Night
Increasing high clouds in the evening, becoming overcast after midnight. Light to moderate east winds at Pass level increasing overnight.
Wednesday
Mostly cloudy with scattered light rain and snow showers this morning becoming partly sunny this afternoon. Light to moderate west winds at Pass level.
Wednesday
Night
Increasing high clouds in the evening, becoming overcast after midnight. Moderate east winds at Pass level increasing overnight.
Wednesday
Cloudy this morning becoming partly to mostly sunny this afternoon.
Wednesday
Night
Clear early, then increasing high clouds and becoming overcast late.
Wednesday
Mostly cloudy this morning becoming mostly sunny this afternoon. A few showers near the Cascade crest early this morning.
Wednesday
Night
Clear early, then increasing high clouds and becoming overcast late.
Wednesday
Partly to mostly cloudy this morning becoming mostly sunny this afternoon. A few showers near the Cascade crest early this morning.
Wednesday
Night
Clear early, then increasing high clouds and becoming overcast late.
Wednesday
Mostly cloudy with scattered light rain and snow showers this morning. Partly sunny this afternoon west-side, mostly sunny east-side and upper mountain. Strong winds this morning easing in the afternoon.
Wednesday
Night
Increasing high clouds in the evening, becoming overcast after midnight.
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).