Hazards may be higher than forecast on solar aspects in the afternoon. Pay close attention to danger from cornices.
Confidence
Fair - Forecast snowfall amounts are uncertain on Tuesday
Weather Forecast
Synopsis: An arctic high pressure ridge in the interior of BC will keep the temperatures cool before the next Pacific frontal wave arrives on Tuesday.Tonight: Cloudy, no precipitation in the forecast, freezing level around 800 metres, winds light, from the south west.Monday: Cloudy with flurries, trace of precipitation, freezing level around 1400 metres, winds light to moderate from the east,-south east.Tuesday: Cloudy with snow, 10 to 15 cm in the forecast, freezing level around 1600 metres, winds light mostly from the south.Wednesday: Cloudy with flurries, trace of precipitation in the forecast, freezing level around 1500 metres, light to moderate ridge top winds from the south west.
Avalanche Summary
Few reports of avalanche activity from yesterday. Reports of glide/rock slab releases on steep solar aspects during brief sunny period. These steep south aspects will be of concern in the afternoon. Conditions appear to be improving, but It's still too early to be stepping up to bigger objectives.
Snowpack Summary
Recent storm snow appears to be bonding well in the upper snow pack while increasing the load sitting on the persistent weak layers. The two persistent weak layers that remain a concern are:The March weak layer. A combination of hard wind-scoured slab surfaces in exposed terrain, facets and/or surface hoar in sheltered and north aspects, and sun crust on steep solar aspects and is generally widespread throughout the forecast region. This layer is now down between 70 and 80cm from the surface.A late January/early February crust/facet/surface hoar combo that is still showing up in snowpack tests with hard shear tests, now down 150 to 250cm from the surface. Recent warming temperatures will be good for bonding above and below this layer, but a sudden increase in load, a cornice failure, or a big rain event could "wake up" this layer and result in large avalanches. There are also basal facets at the bottom of the snowpack from cold clear weather in early December, but for the most part these have not been a concern, however, recently, a few large avalanches have stepped down to the basal facets and the ground.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.