Windslabs continue to be a problem for human triggering in the alpine and at treeline where the changing winds have transported snow and scoured down to the icy crust.
Confidence
Poor - Timing, track, or intensity of incoming weather system is uncertain on Friday
Weather Forecast
Clear overnight with light winds and overnight alpine temperatures around -12. Clear on Wednesday with light winds and freezing levels rising up to about 1500 metres. Cloud developing during the day on Thursday. Increasing Southwest winds Thursday evening combined with snow. Cloudy with snow and strong Southerly winds on Friday.
Avalanche Summary
No new avalanches reported.
Snowpack Summary
Surface hoar and near surface facets are reported to be growing during the cold and clear weather. Strong Northeast outflow winds developed windslabs 10-40 cm deep since Friday, and then strong and variable winds have since loaded and reverse loaded the light dry snow that came at the end of the storm. Below this new snow is a solid weight bearing crust in all but the highest alpine slopes. There is a chance that a consolidated slab exists in some areas in the alpine above a deeply buried crust from earlier in November.
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.