Weaknesses deep the in the snowpack can be triggered from shallow areas or by large triggers. Daytime and solar heating will weaken cornices, avoid traveling under or to close to them.
Weather Forecast
Light flurries Monday afternoon with a mix of sun and cloud, light winds from the NW. Freezing level up to 1600m with an alpine high of -5. Clear skies and warming temps for Tuesday and Wednesday.
Snowpack Summary
12cm new snow in the past 36hrs, winds gusting to 60km/hr from SW building slab. The mid-pack is bridging the basal weakness, which consists of weak facets, depth hoar and the Nov rain crust. Isothermal conditions below tree-line on solar aspects.
Avalanche Summary
Recent cornice and windslab failures have triggered the deep persistent slab creating large full path avalanches that are traveling into valley bottoms. Loose wet avalanches have been occurring on steeper south and west aspect below tree-line.
Confidence
Timing or intensity of solar radiation is uncertain on Tuesday
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.