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Avalanche Forecast

Archived

Dec 31st, 2019–Jan 1st, 2020

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

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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. 

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.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). 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.