Fresh storm slabs will likely be reactive to human triggering, especially in wind loaded areas, and at upper elevations. Watch for signs of instability such as whumphing, cracking and recent avalanches.
Weather Forecast
FRIDAY NIGHT - Clear periods / east winds 10-15 km/h / alpine low temperature near -27SATURDAY - Mainly sunny / east winds 10 km/h / alpine high temperature near -21SUNDAY - Sunny / northeast winds 10-20 km/h / alpine high temperature near -16MONDAY - Sunny / northeast winds, 15-30 km/h / alpine high temperature near -13
Avalanche Summary
There were reports of numerous size 1-1.5 avalanches on Friday. They were natural, human, and explosives triggered.A few natural loose snow avalanches were reported on Thursday.A few natural wind slab avalanches size 1.5-2 on northwest aspects were reported on Wednesday.On Monday, size 1 natural and human triggered wind slab avalanches were reported on all aspects at treeline and in the alpine. Last Saturday, numerous natural and explosives triggered storm slab avalanches to size 2-2.5 were reported on north and east aspects in the alpine and treeline. These avalanches were 50-100 cm deep.
Snowpack Summary
Up to 30 cm of new snow combined with winds will be forming fresh storm slabs. The new snow sits on older wind slabs at upper elevations, which will be difficult to detect now that they are buried. In sheltered areas and below treeline, the new snow sits on facets (sugary snow) surface hoar (feathery crystals) and a crust on south facing slopes.There are potentially three weak layers of surface hoar in the top 100 cm of the snowpack. One is down 30-50 cm, another is down 40-80 cm and the last one is down 80-110 cm. These layers are most prominent between 1600-1900 m.The lower portion of the snowpack is considered generally strong.
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.
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.