Expect to continue to see reactive storm slabs on Sunday with the 50-60 cm of new snow that fell Friday night.
Confidence
High - The weather pattern is stable
Weather Forecast
SUNDAY: Sunny with cloudy periods / moderate east wind / alpine temperature -15MONDAY: A mix of sun and cloud / light to moderate east wind / alpine temperature -17TUESDAY: A mix of sun and cloud / light northeast wind / alpine temperature -15
Avalanche Summary
Numerous natural and explosives triggered storm slab avalanches to size 2 and 2.5 were reported on Saturday. These were 50-100 cm deep running on east through north aspects in the alpine and treeline.An explosive triggered a large (size 2.5) persistent slab avalanche on Thursday. It was on a southerly aspect and between 1650 and 2000 m. The slab was about 40 cm deep.
Snowpack Summary
Up to 60 cm of low density new snow sits on wind affected surfaces in the alpine and treeline. In sheltered areas, the new snow is burying faceted surface snow and possibly a layer of surface hoar. In sheltered areas between 1600 and 1800 m, another weak layer of surface hoar crystals buried around Valentines Day, is now 60-80 cm below the snow surface.Two more weak layers of surface hoar may be found within the snowpack. One buried early-February, is 80-100 cm deep in shaded and sheltered areas above 1600 m. The other buried mid-January, is 100-150 cm down and is most prominent between 1600 m and 1900 m.The remainder of the snowpack is well-settled.
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.