The Bottom Line: Wednesday brought more than 30″ of new snow to this zone, combined with strong SE winds in the alpine. Reactive slabs of wind drifted snow in the alpine will be multiple feet thick. These slabs rest on weak storm snow and facets. Human triggering is likely on slopes steeper than 30 degrees. Wind slabs can be avoided by sticking to sheltered or wind-scoured areas. Also from the wind, cornices might be unsupported, scoured, and weak. Tread carefully around them and limit your exposure to slopes below them. A cornice drop could cause a slide, with potential for a step down.

The severe consequences of our avalanche problems remain, due to deep persistent layers. Be hypersensitive of terrain- it is an active way to manage our exposure to the risk of an unlikely but high-consequence deep slab avalanche.

When on or near avalanche terrain, be diligent on terrain selection, group management, and human factor.  Travel one at a time or with enough spacing so that only one person is exposed to an avalanche path at any one time. Be prepared for an avalanche that could step down to deeper instabilities, creating a slide that could break very wide, and take out all the “safe” zones on a slope. Be extra careful not to group up in places that an avalanche can reach. 

When seeking out wind protected zones, remember that wind-protected pockets may be harboring weak, buried surface hoar layers. Protected means preserved. 

Jan 25th melt freeze crust is ~4-5′ deep sitting on top of it are near surface facets, and buried surface hoar from Feb 1-4.

Snow pit from Feb 22 in Lutak (NE aspect 1800ft) showing persistent weak layers below the snowfall from Feb 10-15.

Cornices have become very large and weak. They are undercut, overhanging, and slowly sagging as they grow. Strong sunshine and increasing winds will put a lot of stress on these dangerous beasts. Stay way back from any snow ledges or cornices on ridgelines or summits. Some may fall naturally, so do not travel below them. More likely will be human triggering of cornices from above. When a cornice fails, it will break way further back on the ridge than expected and take most of the flat terrain out with it. Any cornice falls are likely to trigger very large and deadly deep-slab avalanches. Consequences are very high right now!

An unlikely to trigger, but high consequence deep slab layer remains. The “Big Warm-Up layer” from Nov 17th is not to be forgotten about. Although currently dormant, a smaller slide triggered on the upper snowpack could step down and trigger this deadly beast.

Lutak, Feb 4 PST 70/130 End down 130 rounding faceted polycrystals.