The recent storm snow is expected to be very touchy on Tuesday, especially in wind loaded terrain. Conservative terrain selection remains critical. If the sun comes out in the afternoon, avoid all sun exposed slopes.
Weather Forecast
Lingering flurries are possible on Tuesday morning and a mix of sun and cloud is expected for Tuesday afternoon. Alpine wind is forecast to be moderate from the west and treeline temperatures are forecast to be around -15C. A mix of sun and cloud is expected on Wednesday with moderate alpine wind from the west and treeline temperatures around -15C. The next storm system is currently forecast to arrive on Wednesday night and 10-20 cm of snowfall is forecast for Thursday with strong southwest wind and freezing levels climbing to around 1500 m elevation.
Avalanche Summary
An early report from Monday includes several explosive triggered storm slab avalanches up to size 2. These were typically 30-60 cm thick slabs. On Sunday, natural and human triggered avalanches up to size 3 were observed on all aspects and elevations above around 1500 m. Slabs were typically 30-40 cm thick with the thickest being up to 80 cm. A few remotely triggered avalanches were also reported with the furthest being triggered from 50 m away. The recent storm snow is expected to remain very touchy on Tuesday, especially where it has been redistributed by the wind. Buried surface hoar, facets, and/or a sun crust may increase the reactivity and propagation propensity of these storm slabs.
Snowpack Summary
Around 70cm of storm snow has accumulated over the weekend. Strong shifting winds have redistributed the new snow in exposed terrain forming very touchy wind slabs. The new snow overlies a highly variable old surface which may include wind affected surfaces, a layer of surface hoar in sheltered areas, facets, and/or a thin sun crust. Recent reports suggest a poor bond between the new snow and the old surface. The mid and lower snowpack are generally well settled and stable but isolated basal weaknesses may exist in shallow snowpack areas.
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.