West Slopes Central

The stretch of sunshine and abnormally warm temperatures will end Sunday marking the transition to a more active weather pattern. Generally, safe avalanche conditions will exist where you encounter firm and frozen snow surfaces. Even though avalanches will be unlikely, watch for signs of instability during periods of rain and in wind-loaded terrain high in the alpine. 

A weak frontal system will bring cooling temperatures and light precipitation (4000-5000ft snow levels) by Sunday morning. Expect cloudy skies and light rain in most areas with not enough high elevation snow to create new avalanche problems. Snow surfaces at mid and lower elevations may not experience a solid overnight freeze and have the best chance of becoming wet and weak. With any incoming rain during the day, watch for signs of instability like roller balls and pinwheels. High in the alpine, look carefully for evidence of wind drifted snow before committing to steeper terrain.

Despite the short days and low angle of the sun in December, solar radiation and unseasonably warm air significantly impacted the snowpack this week. Many NWAC weather stations throughout the west slope of the Cascades recorded steady temperatures well above freezing since Tuesday night (12/1). During this time, observers reported small but widespread wet avalanche activity, even extending to northerly aspects at upper elevations. The wet avalanche cycle peaked on Wednesday during the initial warm-up, but minor wet loose activity continued through Saturday on steep, sun-exposed slopes. Glide cracks and small glide avalanches were reported as well in areas where thin snow covers smooth rock surfaces. Fortunately, the snowpack was resilient to all the heat with only a few inches of snowpack settlement and even reports of dry snow lingering on shaded upper elevation slopes. 

Snow depths throughout the west slope of the Cascades range from 40-70 inches and continuous snow begins near 2500-3000ft. Even though the current snow coverage is well above average for December (Snow Depth Climatology), early season conditions still exist. Stay alert for open creeks, tree wells, crevasses, or other exposed hazards. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.