A weak front passed through the area this morning. Light to occasionally moderate post-frontal snow showers will rotate from SW to NE across the area as the parent low pressure center drops south along the coast from Vancouver Island to off of Gray's Harbor by this afternoon. Showers may take a bit of breather mid-day before an upper level feature rotating around the base of the low reinvigorates shower activity later this afternoon especially over the southwest Washington Cascades and Mt Hood. Strong westerly ridgeline winds can be found from the far southern Washington Cascades to Mt hood, with lighter winds for areas further north.
The low pressure system will slide inland tonight, and there is quite a bit of uncertainty for how much snow is produced along the west slopes of the Cascades as it moves inland. Besides the weather system, very cold air bottled up in interior Canada will start to leak out late tonight and tomorrow through the Fraser Valley, creating the opportunity to squeeze out even more low density fluff where ever the two pieces collide.
On Christmas day, look for another low pressure system to slide down the coast and spread light to occasionally moderate snow showers over most areas once again by Saturday afternoon. Snow levels will fall to near sea-level even on the west side of the Cascades by Saturday afternoon with the coldest temperatures yet to come. That said, temps will struggle in lower teens across the North Cascades on Christmas day as the arctic intrusion begins in earnest.
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
Light to occasionally moderate snow showers. A few sunbreaks possible.
Friday
Night
Light snow showers.
Friday
Light to occasionally moderate snow showers in the morning. Scattered snow showers in the afternoon.
Friday
Night
Light to occasionally moderate snow.
Friday
Light to occasionally moderate snow showers in the morning. Scattered snow showers in the afternoon.
Friday
Night
Light to occasionally moderate snow.
Friday
Light to occasionally moderate snow showers in the morning becoming scattered mid-day. Showers increasing again late in the day. Strong ridgeline winds far southern Cascades.
Friday
Night
Light to occasionally moderate snow.
Friday
Light to occasionally moderate snow showers in the morning becoming scattered mid-day. Light east winds at Pass level.
Friday
Night
Light snow. Light east winds at Pass level becoming westerly after midnight.
Friday
Light to occasionally moderate snow showers in the morning becoming scattered mid-day. Light east winds at Pass level.
Friday
Night
Light snow to occasionally moderate snow. Light east winds at Pass level becoming moderate westerly after midnight.
Friday
Cloudy with scattered snow light showers.
Friday
Night
Cloudy with scattered snow light showers.
Friday
Cloudy with scattered snow light showers, occasionally moderate near the Cascade crest.
Friday
Night
Cloudy with scattered snow light showers.
Friday
Light snow showers in the morning becoming scattered mid-day. Showers increasing again late in the day.
Friday
Night
Cloudy with scattered snow light showers.
Friday
Moderate to heavy snow showers in the morning becoming light to occasionally moderate in the afternoon. Strong ridgeline winds.
Friday
Night
Light snow to occasionally moderate snow showers. Strong ridgeline winds.
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).