A weak upper trough will cause bands of light precipitation to rotate from south to north over the region this morning. We should see a mix of sun and clouds mid-day through early afternoon before high clouds from the next system float overhead later in the afternoon. Low clouds are more likely to hang around east of the Cascade crest for the remainder of the day.
An atmospheric river will start to take aim at the region Wednesday night into Thursday. Warm frontal moisture will lift from south to north over the area. The flow aloft will turn more southerly, with the heaviest precipitation favoring the Olympics and Mt Baker area. Areas near and south of Stevens Pass should see precipitation lighten Thursday afternoon. A warming trend will begin late Wednesday night and continue through Thursday, with many trailheads and lower elevation sites turning from snow to rain. The east slopes of the Cascades and Stevens Pass will hold on a bit longer to snow. Additional waves of precipitation will affect the region through Friday.
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
Period of rain and snow in the morning, then partly sunny mid-day. High clouds increasing later in the afternoon.
Wednesday
Night
Cloudy with light to moderate rain and snow developing after midnight. Winds increasing overnight.
Wednesday
Period of rain and snow in the morning, then partly sunny in the afternoon.
Wednesday
Night
Cloudy with light to moderate rain and snow developing after midnight. Winds increasing overnight.
Wednesday
Period of rain and snow in the morning, then partly sunny mid-day. High clouds increasing later in the afternoon.
Wednesday
Night
Cloudy with light to moderate rain and snow developing after midnight. Winds increasing overnight.
Wednesday
Period of rain and snow in the morning, then partly sunny mid-day. High clouds increasing later in the afternoon.
Wednesday
Night
Cloudy with light to moderate rain and snow developing late in the evening. Winds increasing overnight.
Wednesday
Period of rain and snow in the morning, then partly sunny mid-day. High clouds increasing later in the afternoon. Light to moderate E-SE winds both at Pass and ridgeline.
Wednesday
Night
Cloudy with light to moderate rain and snow developing after midnight. E-SE Pass level and ridgeline winds increasing overnight.
Wednesday
Period of rain and snow in the morning, then partly sunny mid-day. High clouds increasing later in the afternoon. Period of rain and snow in the morning, then partly sunny mid-day. High clouds increasing later in the afternoon. Light to moderate E-SE winds both at Pass and ridgeline.
Wednesday
Night
Cloudy with light to moderate rain and snow developing late in the evening. E-SE Pass level and ridgeline winds increasing overnight.
Wednesday
Chance of light snow in the morning, then partly to mostly cloudy in the afternoon.
Wednesday
Night
Cloudy with light to moderate rain and snow developing late. Winds increasing overnight.
Wednesday
Period of rain and snow in the morning, then partly sunny mid-day. High clouds increasing later in the afternoon.
Wednesday
Night
Cloudy with light to moderate rain and snow developing late in the evening. Winds increasing overnight.
Wednesday
Period of rain and snow in the morning, then partly sunny mid-day. High clouds increasing later in the afternoon.
Wednesday
Night
Cloudy with light to moderate rain and snow developing late in the evening. Winds increasing overnight.
Wednesday
Partly sunny in the morning, then becoming overcast with increasing high clouds in the afternoon.
Wednesday
Night
Cloudy with moderate to occasionally heavy rain and snow developing in the evening. Winds increasing overnight.
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).