Regions
Kootenay Boundary.
New snow and wind over the past 36 hours has created a touchy storm slab problem. This will require a few days to settle and stabilize as we head into a more stable weather pattern to end the weekend.
Confidence
Moderate - The weather pattern is stable
Weather Forecast
SATURDAY NIGHT: Flurries, accumulation 5-10cm / Moderate west and northwest wind / Alpine temperature -8 CSUNDAY: Mostly cloudy with sunny breaks / Moderate northwest wind / Alpine temperature -7 C MONDAY: Mix of sun and cloud / Light north wind / Alpine temperature -9 CTUESDAY: Mix of sun and cloud / Light west wind / Alpine Temperature -6
Avalanche Summary
Recent reports indicate widespread thin storm slab avalanche activity size 1-1.5 that were 15cm deep with a some avalanches running to size 2 where thicker wind deposits existed (up to 40 cm). These were reported as explosives triggered, naturally triggered and some skier controlled.
Snowpack Summary
20-40 cm of snow sits on a thin sun crust on southerly aspects and small feathery surface hoar in sheltered areas.Beneath this, around 50 to 100 cm of snow is poorly bonded to a rain crust and a weak layer of feathery surface hoar and sugary facets. Although there has not been a reported avalanche on this layer for about a week, snowpack test results tell us that it is still possible to trigger. It is best to remain conservative and travel cautiously with this layer in the snowpack.The lower 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.