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.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
Banff Yoho Kootenay.
Extensive wind transport across the forecast region has re-loaded wind slabs that were touchy to begin with. Conservative terrain choices will be important over the next few days in order to avoid encounters with avalanches.
Weather Forecast
Above zero temperatures are forecasted to start on Monday. Thankfully the wind will die down to the moderate range at the 3000m level. All of the aforementioned conditions will be accompanied by clearing skies and lack of precipitation.
Snowpack Summary
30-60cm of new snow in the past 10 days with extreme winds from the SW have created new slabs over a weak snow pack comprised mostly of facets, buried wind layers, and depth hoar. We expect more avalanches on these weak facet layers over the next while as the snowpack adjusts to the load.
Avalanche Summary
Strong to extreme wind has produced another avalanche cycle. A size 3 avalanche ran over the Bourgeau Left ice climb going full path. Also, a size 3 near Bow summit was observed by forecasters this morning. Photo here.
Confidence
Due to the number and quality of field observations on Sunday
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.
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.