We'll have a mostly sunny and cold start to the day in the mountains; mountain temperatures are in the teens with even a few single digits around. Winds will remain on the lighter side as an upper-level ridge positioned offshore flops over the area today. We won't squeeze out a completely sunny day as high clouds from the next frontal system upstream of our area begins to move in during the day. We'll see some filtered sunshine for the Olympics and west slopes of the Cascades in the afternoon and more sunshine for areas south of I-90 along the east slopes of the Cascades and Mt Hood.
A frontal system will move toward our area tonight, spreading light precipitation inland after midnight with S-SW winds increasing quickly for the Olympics and northwest Cascades. Precipitation will increase rapidly Thursday morning with an occluded front passing through the central Cascades around 9 am. Post frontal showers in cool northwesterly flow aloft will start to churn out moderate snow showers near and west of the Cascade crest. Locally higher snow amounts are possible if a convergence zone forms. Westerly ridgeline winds will be strong starting mid-morning for all areas. This pattern of wind and significant snow showers will continue 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
Mostly sunny with periods of high clouds becoming high overcast in the afternoon.
Wednesday
Night
Cloudy with light rain and snow developing in the evening and increasing after midnight. Increasing ridgeline winds overnight.
Wednesday
Mostly sunny with periods of high clouds becoming filtered sunshine in the afternoon.
Wednesday
Night
Cloudy with light snow developing late in the evening and increasing to light to moderate after midnight. Increasing ridgeline winds overnight.
Wednesday
Mostly sunny with periods of high clouds becoming filtered sunshine in the afternoon.
Wednesday
Night
Becoming cloudy in the evening with light snow developing after midnight.
Wednesday
Mostly sunny with periods of high clouds becoming filtered sunshine in the afternoon.
Wednesday
Night
Becoming cloudy in the evening with light snow developing after midnight.
Wednesday
Mostly sunny with periods of high clouds becoming filtered sunshine in the afternoon. Light west winds at Pass level.
Wednesday
Night
Becoming cloudy in the evening with light snow developing after midnight.
Wednesday
Mostly sunny with periods of high clouds becoming filtered sunshine in the afternoon. Light west winds at Pass level.
Wednesday
Night
Becoming cloudy in the evening with light snow developing after midnight.
Wednesday
Mostly sunny with periods of high clouds becoming filtered sunshine in the afternoon.
Wednesday
Night
Becoming cloudy in the evening with light snow developing after midnight.
Wednesday
Mostly sunny with a few high clouds and filtered sunshine late.
Wednesday
Night
Becoming cloudy in the evening with light snow developing after midnight.
Wednesday
Mostly sunny with a few high clouds and filtered sunshine late.
Wednesday
Night
Partly cloudy in the evening then becoming cloudy with a chance of light snow late.
Wednesday
Mostly sunny with a few high clouds and filtered sunshine late.
Wednesday
Night
Partly cloudy in the evening then becoming cloudy with a chance of light snow late.
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).