Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Regions
Jasper.
We have a very complicated snowpack that will require a careful and conservative assessment before committing to any avalanche terrain. Ice climbs with significant overhead hazard should be avoided until the hazard abates.
60cm of new snow has fallen since Dec. 11th in the Icefields, south to Rampart Creek areas (much less to the north), and has been redistributed by moderate SW wind. The resulting storm and wind slabs overly several weak interfaces - facets, crusts and isolated surface hoar. A deep persistent weaknesses still lingers in the bottom of the snowpack.
Avalanche Summary
A natural avalanche cycle triggered by this weeks storm resulted in numerous storm and wind slab avalanches up to size 3.5. Avalanche control work in the Parkers ridge area on Friday (Dec. 14th) produced numerous slab avalanches up to size 2.5 - direct evidence that despite natural triggering having slowed, human triggering remains likely.
Confidence
Problems
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.
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.