Human-triggered avalanches are likely wherever a slab sits over the deeper facet layers. This is not a problem you can outsmart, and the ways to reduce risk are through avoidance of avalanche terrain or choosing slopes where the consequences of an avalanche will be smaller.
Slabs typically 25-60cm thick overly faceted snow (Dec. 17th weak layer) that was on the surface during the prolonged deep freeze. If initiated, the big concern is that it can step down to the deeper weak layers. Below treeline the problem exists only where there is a slab overlying the deeper weak layers.
Much of the bottom half of the snowpack is very weak and faceted. Avalanches have been initiated on this layer, or starting higher in the snowpack and "stepping down" to the basal facets causing large avalanches
Avalanche control over the last few days has produced large avalanches up to size 3 in many different areas. Some were initiated on the Dec. 17 interface but most stepped down to the basal facets. Lake Louise ski hill triggered numerous slides with explosives today, including a size 3 in Boundary Bowl. It slid on the basal facets and produced debris up to 3.5m deep. Visitor Safety Specialists remote-triggered a size 2.5 from a ridge on Mt. Simpson Thursday, and there was also a skier-triggered incident on Bow Peak which luckily just resulted in lost gear. Flights today and yesterday observed a natural cycle that occurred sometime in the past week up to size 2.5.
Slabs 25-60cm sit atop a weak layer of facets and surface hoar (Dec. 17th interface). Below this, the snowpack is generally facetted with the weakest facets and depth hoar near the bottom. Snowpack depths at treeline range from 80-150cm throughout the region.
Some light snow overnight into Saturday AM with up to 5cm overnight in the Little Yoho area, and less to the East. On Saturday expect a few cm with most in Little Yoho, 30-40km/h West ridgetop winds, and valley bottom freezing levels. Flurries will die off Saturday night, with winds shifting to West-Northwest in the 30-40 km/h range at ridgetop.
