A frontal system and associated trough passing through central British Columbia clips the Pacific Northwest on Friday morning. The tail of that front has brought widespread high and mid-level cloud cover to our region and cooler temperatures along with decreasing light to moderate WNW winds. Behind that front, the tail edge of a warm front rounds the offshore ridge and should bring an increasing threat of isolated very light snow showers. These can be seen reaching coastal Washington and will bring a dusting to half an inch of snow to the western Olympic Mountains and to areas west of Mt Baker, with snow levels 1000-2000 ft. Temperatures dropped into the low to mid 30s in most lowland locations and into the 20s in most mountain locations overnight. Freezing levels should rise up to around 3000-4000 ft in other portions of Washington State by the afternoon and as high as 6000 ft for Mt Hood.
The general pattern remains similar Friday night with the warm front bringing a slightly increased chance of flurries or light snow to the Mt Baker area. The ridge begins to rebound back into our area, so Friday night won't be quite as cool as Thursday night.
Saturday should be milder west of the Cascade Crest as the ridge of high pressure expands further, bringing mostly sunny skies and cutting off the snow shower activity. Expect inversions that formed in deep valleys and east of the Cascades to persist into the late morning hours.
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
Mostly cloudy with scattered very light snow showers focused on the western part of the range.
Friday
Night
Mostly cloudy with scattered very light snow or snow showers focused on the western part of the range.
Friday
Mostly cloudy with a few very light snow showers or flurries focused on the western part of the zone.
Friday
Night
Mostly cloudy with scattered very light snow or snow showers.
Friday
Mostly cloudy.
Friday
Night
Partly to mostly cloudy.
Friday
Partly cloudy. Temperature inversions in valley locations through mid-morning.
Friday
Night
Partly cloudy. Also some mid and high cloud cover.
Friday
Partly cloudy. Light ridgeline and W wind at the Pass.
Friday
Night
Partly cloudy. Also some mid and high cloud cover. Light ridgeline and variable wind at the Pass.
Friday
Partly cloudy. Light ridgeline and W wind at the Pass.
Friday
Night
Partly cloudy. Also some mid and high cloud cover. Light ridgeline and variable wind at the Pass.
Friday
A few low clouds near the pass, otherwise, expect filtered sunshine with some mid and high clouds.
Friday
Night
Some mid and high cloud cover.
Friday
A few low clouds near the Cascade Crest, otherwise, expect filtered sunshine with some mid and high clouds.
Friday
Night
Some mid and high cloud cover.
Friday
A few low clouds near the Cascade Crest, otherwise, expect filtered sunshine with some mid and high clouds.
Friday
Night
Mostly clear with some high and mid-level clouds.
Friday
Mostly sunny with a few high clouds at times. Moderate ridgeline winds early, becoming mostly light.
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).