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 possible, human triggered probable.
Regions
Banff Yoho Kootenay.
Avoid all avalanche terrain until things improve! We expect natural avalanche activity to taper off by the end of Saturday, but the likelihood of human triggering will remain high for some time.
Weather Forecast
A strong Westerly flow will continue for the next couple of days with a few flurries on Saturday and a drying trend for Sunday. Alpine winds continue to be in the Moderate to Strong range with a dip in temperatures overnight Friday down to the low teens, and a gradual rise in temperatures over the next several days.
Snowpack Summary
10-25cm of new snow with extreme winds from the SW and warming temperatures, have created new snow slabs over a fundamentally weak snowpack comprised mostly of facets and depth hoar. Snowpack tests indicate failures, numerous avalanches have been observed, and we expect more avalanches on these weak facet layers over the next 24hrs.
Avalanche Summary
Numerous natural avalanches were observed and reported throughout the forecast region up to size 3 in the last 24hrs. These have been a mix of loose dry avalanches in steep gullies, wind loaded slopes in the alpine and at treeline, and deep persistent slabs triggered by the wind slabs and loose dry avalanches.
Confidence
Due to the number and quality of field observations
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
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.