A quasi-stationary frontal band is currently located just west of the Olympic Peninsula this morning and oriented in an N-S fashion. A warm front associated with this boundary lifted north overnight, bringing an increase in SE winds and a brief burst of heavy precipitation to the Mt Baker area with drier conditions elsewhere. The frontal boundary will continue to pummel the Olympics with moderate precipitation and strong winds this morning as it slowly slides inland mid-day. The Quillayute coastal sounding at 4 am this morning showed winds at 4500' at S 77 knots, an impressive band of pre-frontal winds that will push inland today. Precipitation will hold off for the Passes and east slope of the Cascades this afternoon. Until the precipitation starts, freezing levels will stay elevated, and then come down to 4000-5000' across the region.
The front will push through tonight with post-frontal showers focused on the Olympics and the northwest Cascades in SW flow aloft. Snow levels will drop to 2000-2500' by early Saturday morning and winds will ease after midnight. Weak upper-level trough will swing through on Saturday and help keep scattered but light showers in the forecast. Look for cloud cover to generally increase in the afternoon for areas that happen upon sunbreaks in the AM.
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
Moderate rain and snow becoming light to moderate showers in the afternoon. Strong to extreme ridgeline winds decreasing in the afternoon.
Friday
Night
Cloudy with light to occasionally moderate rain and snow showers. Strong ridgeline winds decreasing overnight.
Friday
Light rain and snow re-developing this morning and becoming moderate to occasionally heavy this afternoon. Strong ridgeline winds.
Friday
Night
Cloudy with light to occasionally moderate rain and snow showers. Strong ridgeline winds decreasing overnight.
Friday
Cloudy. Light rain and snow developing late this morning. Strong ridgeline winds developing.
Friday
Night
Cloudy with light to occasionally moderate rain and snow showers. Strong ridgeline winds decreasing overnight.
Friday
Cloudy. Light rain and snow developing late this morning. Strong ridgeline winds becoming extreme in the alpine.
Friday
Night
Cloudy with light rain and snow showers. Strong ridgeline winds decreasing overnight.
Friday
Cloudy. Light rain and snow developing early afternoon. Light to moderate Pass level east winds becoming strong SE at ridgeline.
Friday
Night
Cloudy with light rain and snow showers. Strong ridgeline winds decreasing overnight. Moderate west winds at Pass level.
Friday
Cloudy. Light rain and snow developing early afternoon. Light to moderate Pass level east winds becoming strong SE at ridgeline.
Friday
Night
Cloudy with light rain and snow showers. Strong ridgeline winds decreasing overnight. Moderate west winds at Pass level.
Friday
Cloudy. Light rain and snow developing late this morning. Strong ridgeline winds developing.
Friday
Night
Cloudy with scattered light rain and snow showers. Strong ridgeline winds decreasing overnight.
Friday
Cloudy. Light rain and snow developing early afternoon. Strong ridgeline winds developing.
Friday
Night
Cloudy with scattered light rain and snow showers. Strong ridgeline winds decreasing overnight.
Friday
Cloudy. Light rain and snow developing early afternoon. Strong ridgeline winds developing.
Friday
Night
Cloudy with scattered light rain and snow showers. Strong ridgeline winds decreasing 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).