Snow fall amounts are uncertain on Wednesday; watch for developing hazard during the day.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Wednesday
Weather Forecast
WEDNESDAY: Periods of snow, accumulation 15-20cm Tuesday night through Wednesday / Moderate southwest wind / Alpine temperature -2 / Freezing level 1400 m THURSDAY: Cloudy with sunny periods / Light northwest wind / Alpine temperature -3 / Freezing level 1600mFRIDAY: Cloudy with isolated flurries / Light to moderate southwest wind / Alpine temperature -2 / Freezing level 1200
Avalanche Summary
Reports from Tuesday indicate explosive and skier controlled avalanches to size 2 and 2.5. These were mostly wind and storm slabs failing 10-40cm deep. Some were also triggered by cornices pulling out 20-30cm slabs on slopes below.
Snowpack Summary
Continued light to moderate snowfall is expected to add to the recent storm slabs. 2000m and below, the storm snow lies above a crust that formed last week. A rain crust that was buried around March 15 is now 80-100 cm deep. The mid-February crust/facet layer can still be found at the upper end of tree line and into the alpine. This interface is generally 120-170 cm deep but may be present nearer to the surface in wind scoured areas. Although there is growing confidence that this layer is becoming dormant, a storm slab or cornice release in the right location may have the potential to trigger any of the deeply buried weak layers.
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.
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.