Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
South Coast.
Avoid avalanche terrain on Saturday. Intense snowfall and a reactive crust will make conditions very dangerous.
Confidence
High - on Saturday
Weather Forecast
SATURDAY: Heavy snow starting Friday night with 30-40 cm possible by the end of the day, strong south wind, freezing level around 700 m with alpine high temperatures around -2 C. SUNDAY: Some isolated flurries with clearing throughout the day, moderate northeast wind, freezing level dropping with alpine high temperatures around -6 C.MONDAY: Sunny with cloudy periods, light northeast wind, alpine high temperatures around -10 C.
Avalanche Summary
Storm snow on the crust has been reactive since Wednesday, producing both natural and skier-triggered avalanches in the size 1-2 range at treeline elevations. See here for an example.Expect storm slabs to become much thicker and touchier on Saturday given the poor bond between the new snow and the crust.
Snowpack Summary
Storm snow is accumulating above a hard rain crust that extends into alpine terrain. Reports indicate the snow is poorly bonded to the crust. By Saturday afternoon, storm slabs will likely be over 50 cm thick and become very touchy. There are no significant layers of concern below the crust.
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.