Wide propagation is the theme of the day. The natural activity has stopped, but be aware that human triggering is still likely in steep, windloaded terrain. TL/ALP transitional terrain deserves attention as the snowpack depth is still variable.
Weather Forecast
Winds picking up this evening to the moderate to strong levels at ridge line. Valley bottom winds will be light. Temperatures are expected to remain consistent with today's, a high of -15 in the alpine. No new snow.
Avalanche Summary
A widespread cycle occurred last night and into this morning. For the most part the avalanches were located below cliffs that had continuous spindrift. The spindrift increased the load on the Oct crust, and at the same time it made a slab with enough density to propagate. These avalanches ran far and fast. There were some exceptions. Several avalanches in skiable terrain (sz2) were observed as were numerous loose dry(sz 1) avalanches.
Snowpack Summary
Yesterday's storm snow has settled quickly. 18cm of storm snow as of this afternoon. BTL the trailbreaking is still challenging in untracked areas. At TL and ALP elevations the snowpack is variable in both depth and quality. Any terrain exposed directly to last week's winds is stripped dry with a dusting of storm snow on top. Lee areas are covered with a thick hard slab, which is in turn covered with storm snow. Lots of snow available for wind transport! HS @ Burstall pass: 92cm, HS @ road: 69cm
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.