Confidence
Fair - Timing or intensity of solar radiation is uncertain on Tuesday
Weather Forecast
Sunday night: Light snow. Light W winds. Alpine temperature near -12.Monday: Light snow (5-10 cm). Light W winds, gusting to strong NW. Alpine temperature near -6.Tuesday: No snow. Sunshine. Light SW winds. Alpine temperature near -11.Wednesday: Light snow (10 cm). Light S winds. Alpine temperatures near -4.
Avalanche Summary
Natural avalanche activity, which was widespread during last week’s storm, began to ease on Saturday. Explosives testing triggered three size 2-3 slabs within the storm snow. A snow cat pushing snow triggered a size 2.5 slab, which ran on a SW aspect just above treeline in the backcountry.
Snowpack Summary
New snow is adding weight above deep and cohesive storm slabs which formed last week. These older storm slabs are slowly gaining strength, but are not yet fully settled. Winds from the south through to north-west have formed wind slabs and cornices in the lee of ridges and ribs. A recent rain-soaking weakened the low elevation snowpack, which is likely to become very strong once refrozen.Weak interfaces deeper in the snowpack have become unlikely to be triggered. A facet/crust layer sits at the base of the snowpack.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.