Several layers of faceted snow exist within the snowpack. Blowing and drifting snow over the past 24 hours will put even more stress on these layers. A layer of near-surface facets was buried under the most recent storm snow. This layer is likely sensitive to a person's weight and may be the first place an avalanche fails. Avalanches that start here can step down into deeper, more problematic persistent weak layers both above and below the Christmas rain crust. Avalanches can also initiate on these more deeply buried layers.

Any avalanche that fails below the crust would be large and dangerous, potentially breaking to the ground and taking out the entire season’s snowpack. In many areas near treeline and below, the snowpack remains faceted top to bottom and lacks a cohesive slab. Where a slab does exist, the snowpack structure is poor.

The key is to look for signs of strong snow over weak snow—hard snow over soft snow. If you find a slab, carefully evaluate that slope or avoid it altogether. This problem is most pronounced on north and east-facing slopes, but it also exists on northwest and southeast-facing aspects.

Strong winds blowing from the west on Wednesday formed slabs of wind drifted snow on slopes near treeline and above that face north through southeast. Although these slabs have likely gained some strength, these are the very same slopes that harbor buried persistent weak layers. The additional wind loading will increase the likelihood of human triggered avalanches failing on these weak layers, so I'm going to avoid steep, wind loaded slopes that face N-NE-E-SE.

Strong winds and heavy drifting will have penetrated the near treeline zone as well. Be on the lookout for sensitive drifts further downslope than we might typically expect. Be suspicious of mid-slope terrain features like steep convexities and gully walls.

Heavy snow transport on Wednesday on the north face of Mellenthin.