Regions
Banff Yoho Kootenay.
Despite the fact that temps have dropped the structure of the snowpack is so poor that human triggering still remains likely. Stay in conservative terrain and minimize your exposure to large avalanche terrain.
Weather Forecast
After a cooler day Sunday and some strong solar input, two weak fronts will reach the divide Monday bringing trace amounts of precip. Winds should remain light westerly. Overnight Monday a strong ridge will start to move into the area, skies will clear by midday Tuesday and winds shift to the North. Temperatures will drop but the sun will be strong
Snowpack Summary
Fresh windslabs and cornice growth in the alpine with 30 to 50 cm since the warming a week ago. A 50-100 cm slab overlies the January 6th weak layer of surface hoar, facets and sun crust and snowpack tests indicate an unstable bond between the two. The lower snowpack is facetted and quite weak in thinner areas but is more settled in thicker areas.
Avalanche Summary
A lot of human triggered activity occurred yesterday with a size 3 triggered form the South ridge of Bow Peak being the most eye catching. This event had a crown up to 1.5 m deep,450m wide failing below the cornice at 2600m on the E aspect. An upper slab ran about 250m but one flank continued 1.1km stopping at 1900m. The persistent slab in action..
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.