A north-south oriented frontal band associated with a deep low pressure off the central British Columbia coast will slowly inch closer to the coast today and bring precipitation to the Olympic peninsula by mid-day. Waves of high clouds out ahead of the frontal boundary will make for a mix of high clouds and sunshine through early afternoon for the Cascades before ceilings drop in the mid-late afternoon. S-SE winds have already increased in a few areas this morning and winds will increase further today and tonight. Freezing levels will stay the mildest the longest for areas that stay east of the frontal boundary.
A second wave developing along the same N-S frontal boundary will spread warm frontal precipitation over the north Cascades and Olympics tonight. Precipitation could become moderate or even heavy over the Olympics and Mt Baker area through tomorrow. The central and south Washington Cascades should receive much lighter precipitation totals through this event. The frontal boundary will slowly push inland tomorrow afternoon but will wait until Friday night to pass through the Cascades.
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 this morning. Cloudy with light rain and snow developing mid-day. Strong ridgeline winds.
Thursday
Night
Light to moderate rain and snow. Strong ridgeline winds.
Thursday
Partly to mostly cloudy through early afternoon. Becoming overcast with clouds lowering late this afternoon. Ridgeline winds increasing and becoming strong.
Thursday
Night
Light to moderate rain and snow. Strong ridgeline winds.
Thursday
Partly sunny with periods of filtered sunshine and high clouds through early afternoon. Becoming overcast with clouds lowering late this afternoon.
Thursday
Night
Light to occasionally moderate rain and snow.
Thursday
Partly sunny with periods of filtered sunshine and high clouds through early afternoon. Becoming overcast with clouds lowering late this afternoon. Strong ridgeline winds.
Thursday
Night
Cloudy with occasional light rain and snow.
Thursday
Partly sunny with periods of filtered sunshine and high clouds through early afternoon. Becoming overcast with clouds lowering late this afternoon. Light to moderate east winds at Pass level.
Thursday
Night
Cloudy with occasional light rain and snow. Light to moderate east winds at Pass level.
Thursday
Partly sunny with periods of filtered sunshine and high clouds through early afternoon. Becoming overcast with clouds lowering late this afternoon.Light to moderate east winds at Pass level.
Thursday
Night
Cloudy with occasional light rain and snow. Light to moderate east winds at Pass level.
Thursday
Partly sunny with periods of filtered sunshine and high clouds.
Thursday
Night
Cloudy with occasional light rain and snow.
Thursday
Partly sunny with periods of filtered sunshine and high clouds.
Thursday
Night
Cloudy with occasional light rain and snow near the Cascade crest.
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).