Avalanche Forecast
Regions: Cascades - North West.
Very dangerous avalanche conditions have developed at upper elevations where natural avalanches are likely. Avoid upper elevation terrain and all slopes connected to large avalanche paths. At lower and mid elevations, conservative terrain management will be essential as dense storm slabs or wind-loaded slopes can easily be triggered and may be masked under lower density snow.
Discussion
A juicy storm system unloading on the Cascades has warmed up many of the surrounding areas, but a cold pocket remained over Mt. Baker on Tuesday with heavy snowfall the result. Mt. Baker picked up 9-10†of dense styrofoam-like snow along with sustained moderate winds gusting strong, leading to significant wind transport. In spite of the intense wind loading, the dense snow was not yet showing signs of reactivity.Â
While not known to be a concern at this time, isolated surface hoar was reportedly buried on 12/26. While we don’t know if the layer is active, you might be able to find this layer on sheltered northerly terrain within the top 2 ft or so of snow. If you see signs of large or more widely propagating avalanches at these elevations, please report your findings to NWAC.
With deep snow returning to the West North zone, always ski with a partner and maintain visual or audio communication. For more information on Tree Well and Snow Immersion safety, click here.
Snowpack Discussion
New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.
Avalanche Problems
Storm Slabs
Avoid all avalanche terrain above treeline or connected to higher elevation terrain as a potent storm creates very dangerous avalanche conditions due to high rates of snowfall and wind-drifting. Near and below treeline, much of the avalanche danger will develop under cooling temperatures as heavy snowfall rates create small to large storm slabs. These may mask older wind-slabs from Sunday that we think have largely healed due to mild temperatures on Monday. Any slope with fresh snow deeper than 8” may have a reactive storm slab and the deeper the fresh snow, the more reactive and larger the potential avalanche may be. Check for cohesive layers under lower density surface snow; observe density changes within the storm slab; and look for evidence of old storm slabs.
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 1