Strong winds will probably make the alpine an unpleasant place to be on Tuesday. Watch out for overhead exposure if you end up hiding out at treeline. Natural avalanches will become increasingly likely through the day.
Confidence
High - Due to the number and quality of field observations on Tuesday
Weather Forecast
A necessary reset is on its way, were entering a prolonged period of cold, wet storm systems. TUESDAY: light snow overnight becoming heavy through the day with accumulations of 20-30cm expected, moderate to strong southerly winds 1500m freezing level. WEDNESDAY: heavy snow continues overnight with another 10-20cm expected before the snow stops in the morning, light southwesterly winds, 1500m freezing level. THURSDAY light to moderate snow with moderate southwest winds, 1500m freezing level.
Avalanche Summary
A couple of new size 1-2 wind slabs were triggered naturally and by skiers over the weekend. Cornices large and fragile. They have been reported to be failing naturally and would likely collapse under the weight of a person. I suspect that we will see a widespread avalanche cycle through the storm on Tuesday as the new snow adds load to a variety of untested old surfaces.
Snowpack Summary
New snow and strong winds are going to continue to build fresh soft slabs in the alpine and at treeline. The upper snow pack sits on a widespread crust at treeline and below as well as up to an elevation of about 2200m on aspects that see direct sun. In isolated sheltered north aspects it may sit on pockets of surface hoar or facets. Cornices are large and weak. The midpack is generally well settled.
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.