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.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Regions
Banff Yoho Kootenay.
A weak, early season snowpack dominates the forecast area, and will for the foreseeable future. Triggering full depth avalanches is a real possibility. Stick to well supported lower angle terrain and enjoy the recent snow! CJ
Weather Forecast
Snowfall amounts of 5-10cm are forecast for Sunday night and into Monday accompanied by gusty West winds. Depending on amounts this may increase the avalanche hazard slightly especially in the alpine. Continued flurries and gusty W winds are forecast through Wednesday with alpine temperatures ranging between -7'C and -15'C.
Snowpack Summary
20-30cm of recent snow now sits on top of a generally weak snowpack. Some new wind slabs are present near ridge crests in alpine areas. The lower half of the snowpack is comprised of weak facets and depth hoar. Total snowpack depths range from 60-100 cm, with the deeper snow located on the western side of the forecast region.
Avalanche Summary
Several natural slab avalanches up to size 3 were reported in alpine terrain in Banff and Jasper over the past 36hrs. All of these were failing on the weak basal facets layers near the ground. A skier remote size 1.5 was also reported yesterday on a small steep N facing tree line feature at Bow Summit.
Confidence
Forecast snowfall amounts are uncertain on Monday
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.