Confidence
Fair - Due to variable weather conditions
Weather Forecast
Friday: Expect flurries to taper, yielding a mix of sun and cloud in the afternoon. Winds remain southerly with freezing levels climbing to 1500m. Saturday / Sunday: A weak ridge should keep things dry and relatively sunny with occasional convective flurries and easing southwesterlies until Sunday afternoon, when the next organized system arrives.
Avalanche Summary
Small human triggered windslab events have been reported from lee and crossloaded features at treeline and above. These are isolated to the new storm snow. We also have reports of isolated cornice releases in the high alpine to size 2.0 that did not release deeper layers.
Snowpack Summary
Above 1700m, 25-40cm of new snow now overlies the March 26 interface. This has been accompanied by consistently moderate and at times gusty southerly winds forming windslabs in lee locations. Cornices are huge, and will continue to grow with this weather pattern. The March 26 interface is a crust on all aspects except true north treeline and alpine, where small surface hoar (5mm) is present in sheltered places. The bonds between the new snow and this interface are weak, especially in locations where the surface hoar is present. At lower elevations, the consistent high freezing levels have kept the new snow moist and heavy. Below the newest storm interface, last week's storm snow is well settled and bonded. The deep, persistent early February layers linger in the snowpack and remain a concern with heavy triggers and rapid loading.
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.
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.