Regions
Banff Yoho Kootenay.
By definition the danger rating is considerable on Sunday, however, the backcountry should be approached with caution. More snow is on its way and may bump the hazard rating back to high with minimal input (snow/wind). AB
Weather Forecast
Another system is expected to enter the forecast region starting Sunday. It will deposit approximately 40cm of storm by Tuesday evening. Accompanying the precip is strong westerly wind. We will therefore see a rise in the danger rating after Sunday, likely back to high.
Snowpack Summary
The storm snow from late last week is starting to settle and currently amounts to approximately 60cm. Winds, warm temps causing slab development in exposed areas, which overlies a complex layer of facets, surface hoar and sun crust on solar aspects. Below this a generally well settled midpack overlying the basal depth hoar layer.
Avalanche Summary
Avalanche control today produced many avalanches, but they were smaller than expected. On the Sunshine Road and Vermillion Slide paths on 93S slab avalanches up to size 2 were controlled with explosives. All of these avalanches were sliding on the Jan 30th surface hoar/facets layers approx 40cm deep.
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Monday
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.