The Pacific Northwest gets a break between weather systems. A deformation zone tapers off near the Oregon/Washington border with light snow ending around Mt St Helens by around 9 AM. This feature will continue to bring cloud cover which currently covers the southern 2/3 of our region. These clouds should shift northward as the day progresses as a shortwave ridge moves amplifies over the region. Temperatures started cold throughout the region, but temperatures should warm rapidly over the Olympics and for areas not exposed to the E flow. The Olympics could have freezing levels up to 6500 ft by the afternoon, while an inversion around Mt Baker suggests the warming will occur first at middle elevations.
E winds will ramp up into the moderate range for most areas near the Cascade Crest as ESE winds increase ahead of an approaching warm front and deep offshore low draws flow through the mountain gaps. The strongest winds will be near and just west of the passes with strong to extreme gusts possible in areas exposed to this flow pattern, such as around N Bend. The E winds likely peak Friday evening and very gradually decrease through Saturday, but continue to expect moderate winds in favored areas into the first half of the weekend.
Saturday's warm front arrives from the south with light snow developing first for Mt Hood, the Olympics, and along the E slopes of the Cascades. Snow levels will be near valley bottoms for the E slopes and passes, but range from 3000-5500 ft for warming areas further west.
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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Friday
Sunny to start, then transitioning to mid-level cloud cover and obscured skies.
Friday
Night
Cloudy.
Friday
Mostly sunny. High clouds arrive late in the day. Moderate ridgeline winds at times in the afternoon.
Friday
Night
Mostly cloudy with clouds increasing.
Friday
Mostly sunny. High and mid-level clouds arrive from south to north in the afternoon. Moderate ridgeline winds.
Friday
Night
Mostly cloudy with clouds increasing. Moderate ridgeline winds.
Friday
Mostly cloudy with a chance of very light snow around Mt St Helens in the morning. Moderate ridgeline winds.
Friday
Night
Cloudy. Moderate ridgeline winds.
Friday
Mostly sunny to start with high and mid-level clouds increasing in the afternoon. Increasing moderate ridgeline and light E wind at the Pass.
Friday
Night
Mostly cloudy with clouds increasing. Moderate ridgeline winds.
Friday
Mostly sunny to start with high and mid-level clouds increasing in the afternoon. Increasing moderate ridgeline and light to moderate E wind at the Pass.
Friday
Night
Mostly cloudy with clouds increasing. Moderate ridgeline winds with strong gusts. Moderate E wind at the Pass.
Friday
Mostly sunny.
Friday
Night
Mostly cloudy with clouds increasing.
Friday
Mostly sunny to start, then becoming mostly cloudy in the afternoon. Moderate ridgeline winds develop in some areas during the afternoon.
Friday
Night
Mostly cloudy with clouds increasing. Moderate ridgeline winds.
Friday
Mostly cloudy with a few snow flurries early. Moderate ridgeline winds near the Cascade Crest.
Friday
Night
Cloudy. Moderate ridgeline winds 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).