Another storm tonight and tomorrow will keep danger elevated for Tuesday.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
MONDAY NIGHT: 5-15 cm new snow expected. Strong southwesterly winds.TUESDAY: 10-15 cm additional new snow with freezing level around 1400 m. Strong southwesterly winds.WEDNESDAY: 2-4 cm new snow. Freezing level around 1400 m. Moderate westerly winds.THURSDAY: 5-10 cm new snow, increasing through the day. Freezing level around 1500 m. Moderate southeasterly winds.
Avalanche Summary
Numerous natural and explosives triggered avalanches to size 3.5 and human triggered avalanches to size 2 have been reported in the region daily since Wednesday, December 12. Many of these avalanches were triggered from a distance (remote triggered).A skier was caught in an avalanche on Sunday on a west aspect at around 2000 m on a small slope, which released at a depth of 50 cm on buried surface hoar.
Snowpack Summary
70-120 cm of recent storm snow sits on a weak layer of facets (sugary snow), surface hoar (feathery crystals) and a sun crust (on south aspects). Strong to extreme winds have promoted widespread slab formation.Another weak layer of surface hoar and sun crust that formed in mid November is up to 120 cm below the surface. This layer is most likely to be a problem in areas where the surface hoar sits on the sun crust. This combination is most likely found on steep, south facing slopes at treeline. The potential may exist for smaller avalanches to step down and trigger this deeper layer, resulting in large avalanches.At the base of the snowpack is a crust that formed near the end of October. Concern for this layer is dwindling but it may still be worth considering in places such as steep, rocky, alpine terrain, especially where the snowpack is shallow. It would likely take a large trigger such as a cornice fall to produce an avalanche on this layer.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.