Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
Little Yoho.
New snow, wind and mild temperatures will keep the avalanche danger high on Friday. Avoid traveling in avalanche terrain until things improve. Natural avalanche activity should decrease over the weekend, but human triggering will remain likely!
Weather Forecast
Snow amounts between 10-25cm are expected Thursday night and into Friday morning with mild temperatures and moderate SW winds. A clearing and cooling trend starts on Friday with a ridge of high pressure building for Saturday and Sunday.
Snowpack Summary
A 40-100cm slab of storm snow now sits over the Dec 10th surface hoar/facet interface at treeline and above, with the snowpack almost doubling in the last week. In thin snowpack areas the lower snowpack is weak and faceted with the October 26th depth hoar and crusts near the base. Snow pack depths range from 90-160cm at ~2000m.
Avalanche Summary
Numerous natural avalanches up to size 2.5, as well as several skier remote and skier triggered avalanches up to size 2 have been observed in the last several days. This pattern is likely to continue for the next while.
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Thursday.
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.