Storm slabs on steep slopes, wind slabs on lee slopes and a persistent slab that seems to be "waking up". Plenty to manage but also lots of good snow to ride!
Confidence
Moderate - Due to the number of field observations
Weather Forecast
FRIDAY: Mix of sun and cloud with isolated flurries / Light southeast wind / Alpine temperature -7 / Freezing level 900m SATURDAY: Cloudy with isolated flurries / Light east wind / Alpine temperature -10 SUNDAY: Mix of sun and cloud / Light northeast wind / Alpine temperature -12
Avalanche Summary
Recent avalanche activity has consisted of mainly loose dry in the size 1-1.5 range but also some wind slabs to size 2 in alpine terrain. These were either naturally occurring or intentionally triggered. Deep persistent avalanche activity has become less frequent over the past week.
Snowpack Summary
Up to 60 cm of recent storm snow is being redistributed into slabs in wind-exposed terrain. Below this is a layer buried mid-February that presents as a sun crust on solar aspects, and spotty surface hoar on sheltered slopes. This layer looks most concerning on on solar aspects where it's associated with with small facets or surface hoar above.There are several deeper layers in the mid-pack that have shown signs of improving but remain on the radar as a low probability to trigger, yet high consequence avalanche if triggered. We are talking about surface hoar buried back in December and January. Near the base of the snowpack is a November crust combined with loose sugary snow. These layers may "wake-up" with strong inputs such as sustained warming, sustained snowfall, large triggers (e.g. cornice fall, smaller avalanches coming down from above); human triggering is also possible in shallow snowpack areas with variable snow depth and convoluted terrain.
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.