Investigated one of the large natural D-3 avalanches in the Summit Lake area.
This was on South facing Manitoba (see map). The weak layer in this avalanche
was faceted snow above a crust. Wind loading and new snow tipped the balance.
Large propagation took out most of the snow in the this bowl.
Estimated as a N-HS-R3-D3-O (300-400′ wide, 2-3′ deep, running 1000-1500′)
It is suspect that the old weak facets are responsible for many of the larger
slab avalanches over the Dec 3/4th weekend in the Summit Lake area (possibly
other areas well).