The character of a buried weak layer about 50 cm below the surface is not well known. It could give surprises. A cautious approach to travel is recommended.
Confidence
Moderate - Wind effect is extremely variable
Weather Forecast
Thursday night: 5-10 cm new snow expected.Friday: Flurries. Light northeasterly winds. Treeline temperatures around -12C.Saturday: Dry and sunny. Moderate northwesterly winds. Temperatures around -15C.Sunday: Dry and sunny. Light northwesterly winds. Temperatures around -15C.
Avalanche Summary
A natural avalanche cycle up to size 2.5 was observed on Wednesday with avalanche depths typically 50 cm deep. On Thursday, ski cutting readily released avalanches in wind-loaded terrain on mainly southeast to north aspects.
Snowpack Summary
Around 50cm recent new snow now rests on a variety of old surfaces. These old surfaces include crusts on south through west facing slopes, wind-scoured slopes and, in sheltered terrain at and below treeline, large feathery surface hoar crystals. Lower in the snowpack, you should be able to find a hard crust that was buried near the end of November. This crust is approximately 30cm thick and extends from 1600m to mountain top on all aspects. Average snowpack depths at treeline in the region range from 100 to 140cm.
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.