Regions
Banff Yoho Kootenay.
Lots of new snow loading and natural avalanche activity today. Avoid terrain with overhead hazard and stick to moderate angled, supported terrain. Avalanche control is planned for Mt Bourgeau on Sunday. No climbing in this area on Sunday.
Weather Forecast
Precipitation will taper off on Saturday night but flurries will continue through Sunday with another 5cm expected to fall. Winds should become light to moderate out of the SW and temperatures are forecast to stay below freezing and relatively steady until Monday.
Snowpack Summary
20-40cm of new has fallen with Moderate to Strong SW winds. Lots of wind slabs are present above treeline with new cornice development. This large load of new snow sits on a supportive mid-pack, however the lower half of the snowpack consists of weak facets and depth hoar. Test results show regular failures in the weak facets in the Mod-Hard range.
Avalanche Summary
Poor visibility on Saturday, but natural, skier and explosive triggered avalanches were observed up to size 3 on all aspects running far down the paths. A skier remote size 3 occurred at 2300m on a SE aspect on Observation Peak failing on the Dec facets. Lots of sluffing in steep gullies was observed. Lots of whumphing in thin areas today as well!
Confidence
Due to the number 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.
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.
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.