Recent and wind-drifted snow has added additional stress to buried persistent weak layers increasing the likelihood of human-triggered avalanches in some locations. The danger is greatest on steep, wind-loaded, northerly aspects near treeline and above.

A layer of near-surface facets (NSF) formed during the long December dry spell. This layer is now buried about a foot deep and has been sensitive in recent stability tests. It is especially reactive in areas where the wind has drifted enough snow to form a stiff slab on top. Human-triggered avalanches are most likely to fail here first and could be 1-3 feet deep in drifted areas. It is important to carefully analyze any slope you are considering by digging down to see if the poor structure exists. Avalanches triggered on this weak layer could also step down into our second faceted weak layer at the base of the snowpack. Avalanches failing on this layer would be deep, dangerous, and possibly un-survivable.

In the video below, Dave Garcia demonstrates the reactive potential in our primary layer of concern.

In our travels yesterday, Dave and I investigated a SE aspect at 11,600' where we continued to find the December drought layer as well as facets at the base of the snowpack. Stability tests produced no results but the adage that "structure trumps test results" keeps me leary of this kind of terrain. See the snowpit below.

Strong winds blowing from the north on Wednesday and Thursday have built stiff slabs of wind drifted snow on all aspects near and above treeline, with even some shallow slabs found below. Slabs are becoming more reluctant to release but there is still enough evidence of cracking and collapsing for them to be a problem. Below are some tips for identifying and avoiding wind slabs. Avoid steep terrainn where you can detect recent deposits of wind drifted snow.