This cold snap/drought is making the snowpack more and more complex. Approach terrain with a critical eye and thoroughly inspect the snowpack as you travel.
Weather Forecast
Sunny with no precip. An alpine high of -13 with light west winds.
Avalanche Summary
A size 1.5 natural slab avalanche was noted on Mt Buller. N aspect, alpine start zone. It entrained most of the snowpack on its way down.
Snowpack Summary
Two words: Complex and Variable!! Below treeline the snowpack is shallow and weak. Treeline is where the whole thing gets interesting. The Nov 12th crust is down 60cm and is starting to break down with a fine layer of facets immediately above and below. On top of these new facets, there is a 15cm thick layer of facets that have been growing throughout the cold snap. This thick layer was known as the Nov 24th persistent layer-despite being 15cm thick. To make it more complex, the recent winds have now created a windslab that is on the surface (at treeline). Its thought that the Nov 24th layer will instantly step down to the crust surface if initiated.Now for the alpine...take the treeline story and add yet another windslab to the surface. Working surface down, that leaves us with a surface windslab, followed by a buried windslab, followed by the 15cm thick facet layer...then the Nov 12 crust. Better read that a few times...
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.