Lingering wind slabs are expected to remain reactive to human-triggering on Tuesday. Large cornices will become weak with daytime warming and sun so avoid cornice exposed slopes in the afternoon.
Weather Forecast
A mix of sun and cloud is expected for Tuesday with the possibility of isolated flurries. Freezing levels are expected to reach around 1500m in the afternoon and alpine winds are forecast to be moderate from the southwest to west. Mostly sunny conditions are expected for Sunday with afternoon freezing levels around 1500m and light alpine wind. A weak storm system is currently forecast to bring 5-10mm of precipitation to the region on Thursday with freezing levels climbing to around 2000m.
Avalanche Summary
On Sunday there were several size 1 loose wet avalanches observed below treeline. No other new avalanches were reported, but this may speak to a lack of observers rather than actual conditions. Recent wind slabs are expected to be lingering at higher elevations on Tuesday.
Snowpack Summary
Rainfall on Sunday was reported to around 2100m elevation. The snow surface was reported to be soaked below treeline and dense moist storm snow was reported at treeline. With overnight cooling, a melt-freeze crust is expected at some mid-mountain elevations. In the alpine, strong southwest winds have redistributed the recent storm snow into wind slabs on leeward features. Cornices are also reported to be huge and weak. The mid and lower snowpack are generally well settled and there are currently no major weak layers of concern within the snowpack.
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.
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.