0820: Updated precipitation numbers Timberline, Salmon La Sac, and Mission ridge for the daytime on Saturday.
Temperatures dropped below freezing in many mountain locations Thursday night. Another deep low has moved into the offshore waters with a thick band of cloud cover out ahead of it early Friday morning that extends into much of the PNW region. The leading warm front is stubby and weak, but could touch some light rain/snow for the Olympics this morning before it fizzles out. The stronger feature will be a cold front arriving from the WSW late in the day through the evening hours. As the low center continues to drift northward overnight, the front lingers over the region, allowing southerly winds to continue to bring light showers into the region. Easterly flow picks up on Friday and peaks with the frontal boundary during the evening hours. There's not as much cold air to work with this time around, so expect a mix of rain/snow at lower elevations on both sides of the Cascade Crest.
High-resolution models indicate a slight wave along the frontal boundary that keeps the light rain/snow going early Saturday before precipitation becomes even lighter and more sporadic during the afternoon. Snow levels continue near 3000 ft for most areas.
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
Cloudy with a chance of light rain/snow, primarily late in the day.
Friday
Night
Light rain/snow in the evening, tapering to showers.
Friday
Cloudy with light rain/snow early and again in the afternoon.
Friday
Night
Light rain/snow in the evening tapering to lingering showers.
Friday
Cloudy with a chance of light rain/snow.
Friday
Night
Light rain/snow in the evening tapering to lingering showers.
Friday
Cloudy with a chance of light rain/snow.
Friday
Night
Light rain/snow in the evening tapering to showers.Per
Friday
Cloudy with a chance of light rain/snow. Light ridgeline and W wind switching E at the Pass, may increase into the moderate range late in the day.
Friday
Night
Light rain/snow in the evening tapering to lingering showers. Moderate ridgeline and E wind at the Pass.
Friday
Cloudy with a chance of light rain/snow. Light ridgeline and W wind switching E at the Pass, may increase into the moderate range late in the day.
Friday
Night
Light rain/snow in the evening tapering to lingering showers. Moderate ridgeline and E wind at the Pass.
Friday
Cloudy with a slight chance of very light snow.
Friday
Night
Light snow in the evening with flurries overnight.
Friday
Cloudy.
Friday
Night
Light rain/snow in the evening with flurries/sprinkles overnight.
Friday
Cloudy.
Friday
Night
Periods of light rain/snow.
Friday
Cloudy with a chance of light rain/snow, primarily late in the day.
Friday
Night
Periods of light to moderate rain/snow. Strong wind gusts during the evening hours.
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).