Strong sun on new snow will make conditions touchy today, with solar triggered avalanches and cornice failures expected. Below treeline we are beginning to see a melt-freeze cycle, use caution when the crust is breaking down.
Weather Forecast
Expect mostly dry and clear weather until Friday. Today strong solar with light west winds and an alpine high of -1'C will destabilize the recent storm snow. Thurs will be similar but warmer with freezing levels rising to 2100m, a high 2'C and temps will stay warm overnight. Fri will be increasingly cloudy with showers and freezing levels to 2400m.
Snowpack Summary
Up to 50cm of snow has settled into a slab sitting a crust on solar aspects and surface hoar on sheltered north and east aspects. Wind effected snow at treeline and above. Above 1700m the top 40-50cm is dry with moist or wet snow below it with multiple crusts in the top 1.5m of the snowpack. Sustained warm temps will rapidly weaken the snowpack.
Avalanche Summary
2 size 2 naturals were observed along the highway yesterday, triggered by windloading. On Sunday, skiers triggered slab avalanches to size 1.5 in the Tree Triangle gully at ~2000m, 30-40cm deep, 20m wide and 75m long. In the surrounding region there were reports of cornices triggering slabs, and skier remote's and accidentals to size 2.
Confidence
Timing or intensity of solar radiation is uncertain
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
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.