Regions
Banff Yoho Kootenay.
Conditions have deteriorated and avalanches are occurring - time to pull back on the reins for a few days while the snowpack adjusts. Several large avalanches and burials have occurred over the last 24-hours.
Weather Forecast
No snow is forecast for the next few days, as the skies clear off with only a few clouds but temperatures should remain below freezing. The exception to this rule will be in the sunshine, where intense solar radiation should be anticipated on Tuesday.
Snowpack Summary
The tipping point in the stability of the snowpack has been reached. The past week's 60 cm of storm snow has settled into a slab which is reacting to natural and skier triggers with failures occurring deep in the snowpack. This situation is expected to continue through Tuesday, with extra care advised in all avalanche terrain.
Avalanche Summary
Numerous avalanches were observed in the last 24-hours. An explosive triggered avalanche (size 3.5) released on the ground on Mt. Field; 2 size 3 natural avalanches on Mt Fairview and Cathedral; a size 2.5 skier triggered avalanche at Sunshine, and another natural size 2.5 in Richardson's Bowl at Lake Louise. It's been a big 24-hours of avalanches.
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.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.