Recent strong winds have formed touchy wind slabs. Buried weak layers are also lingering and have recently released large, scary avalanches triggered by skiers. Conservative decision-making is recommended.
Weather Forecast
MONDAY NIGHT: Clearing, freezing level below valley bottomTUESDAY: Clear with afternoon clouds, light southwest winds, alpine temperature -11 C, freezing level below valley bottom.WEDNESDAY: Cloudy with light snowfall, accumulation trace to 5 cm, light to moderate southwest winds, alpine temperature -4 C, freezing level below valley bottom.THURSDAY: Cloudy with light snowfall, accumulation 5 cm, light to moderate southwest winds, alpine temperature -5 C, freezing level below valley bottom.
Avalanche Summary
A large (size 3) avalanche was triggered by a skier in the north of the region. It is likely that it released on weak faceted grains near the base of the snowpack, as described in the snowpack summary.On Sunday, one small (size 1.5) skier triggered avalanche was noted. It occurred in steep terrain above a cliff and the avalanche released to the ground, likely within the weak snow described in the snowpack summary. Otherwise, no new avalanches were observed on Sunday.These reports indicate that basal instabilities are still possible to trigger by humans.
Snowpack Summary
Wind slabs are reported as being widespread in lee and cross-loaded terrain features from recent south to west winds.There are deeper weaknesses in the snowpack. Professionals are still tracking a layer around 80 to 120 cm deep, composed of sugary faceted grains, feathery surface hoar, and a sun crust. The base of the snowpack may also still be composed of weak faceted grains. The likelihood of triggering these deep weak layers is low and would most likely be triggered by humans in areas where the snowpack is shallow.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.