Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Regions
Banff Yoho Kootenay.
Avalanche Control planned for Friday on Mt. Bosworth, Stephen, Field and Dennis. Please no recreational activities in these areas on Friday. Thank-you.
Weather Forecast
Snowfall will taper off Thursday night and winds should back off through the morning Friday. Freezing levels to 1600 m. Expect sunny periods Friday and flurries on Saturday.
Snowpack Summary
20 -35 cm of new snow over the past few days overlies buried sun crusts on solar aspects. Moist snow exists up to 1700 m. Recent moderate S-SW winds with strong gusts have formed slabs in lee areas. A firm upper snow pack sits over a weak mid-pack of facets & depth hoar. In thin snowpack areas tests results are typically collapses near the ground.
Avalanche Summary
A few cornice collapses triggered size 1.5 avalanches in the Sunshine area, otherwise no new avalanches reported, but visibility has been poor. A couple of recent close calls are worth remembering however: last Monday a skier accidental size 2.5 on the Collie Glacier and on Sunday a skier accidental size 2.5 near Bow Summit.
Confidence
Due to the number of field observations
Problems
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.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.