An approaching storm may bump the hazard level up to HIGH. Pay attention to localized conditions. Loose wet avalanches are also possible if warm daytime temperatures and/or intense solar radiation occur.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Tuesday will see the start of a warm and wet storm that could bring as much as 20cm by late Wednesday. Winds will be strong from the SW and freezing levels could reach 2200 to 2300m.
Avalanche Summary
A few naturally triggered size 2 avalanches were observed today in the Alpine on S, E and N aspects. Some of these were cornice triggered. Over the weekend a couple of very large avalanches occurred (up to size 3.5) which ran full-path and also destroyed areas of mature timber. These larger slides have been stepping down to the basal weak layers.
Snowpack Summary
Up to 5cm of new snow fell in the past 24hrs. Wind slabs are present at Treeline and above on all aspects and seem sensitive to human-triggering. Forecasters observed isolated cracking in steep and unsupported convex roles at Treeline today. The biggest concern is the weak basal layers that exist throughout the region. These layers just simply cannot be trusted and all larger features should just be avoided until we go through a few solid melt freeze cycles. Thin melt freeze crusts are being found on solar aspects up to 2400m.
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.
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.
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.