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.
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.
Forecasters experienced a significant whumphf near Dolomite Pass today. A high degree of uncertainty still exists with the weak snowpack.
Weather Forecast
Up to 15cm of new snow and strong west wind is expected at high elevations over the next 48 hours. Temperatures near 2000m should remain at or below freezing. A clearing trend is emerging on the weather models for Friday.
Snowpack Summary
10 cm of snow sits over a solid 100cm+ slab which rests precariously over the weak basal facets at treeline and above. Tests produce consistent sudden collapse results in the facets, and this will not become stronger soon. The surface snow is of a mix of soft snow in the shade, melt-freeze snow below treeline, and sun crust on sun exposed slopes.
Avalanche Summary
Yesterday a size 3 avalanche was reported on the 'Onion Skin' near Bow Hut. A cornice dropped onto a slope which triggered the slide. It was reported that it ran for 800m. Additionally, forecasters experienced a significant whumphf near Dolomite Pass today. A high degree of uncertainty still exists.
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Wednesday
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
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.