Regions
Kootenay Boundary.
Variable snowfall amounts are expected across the region by Thursday, from 10 to 20 cm. The persistent slab problem still exists and is best controlled by diligent group management.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
WEDNESDAY NIGHT: Cloudy with snowfall, accumulation 5 to 15 cm, light to moderate southwest wind, alpine temperature -6 C.THURSDAY: Cloudy with light snowfall, accumulation 2 to 5 cm, moderate southwest wind, alpine temperature -11 C.FRIDAY: Cloudy with light snowfall, accumulation 1 to 3 cm, light to moderate west wind, alpine temperature -11 C.SATURDAY: Cloudy with isolated snowfall, trace accumulation, light northwest wind, alpine temperature -10 C.
Avalanche Summary
Small sluffing was observed in steep terrain on Tuesday. Otherwise, no new avalanches were observed.
Snowpack Summary
Around 10 to 20 cm of new snow is expected to fall Wednesday night into Thursday. This snow will fall on a wind-affected snow surface in exposed terrain, soft and faceted snow in sheltered areas, and a melt-freeze crust on southerly aspects.Two layers of weak and feathery surface hoar crystals are buried in the snowpack between 40 and 80 cm deep, which were buried mid-February and early-February. The layers may be associated with a melt-freeze crust on southerly aspects. These layers remain reactive in snowpack tests and have produced sporadic avalanches in the region over the past week.
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.