April Pow and Slabs

Skied alpine and TL terrain on NE to NW aspects from 2350m to 2000m in the selkirks, east of the kokanee range. 15-25cm of new snow fell in the April 1st storm, forming a soft unreactive 4F slab. Evidence of natural windslab activity during the storm from this new snow in immediate ridgetop lees. HN produced loose dry with skier traffic, that arrested in steep terrain and didn't entrain more mass. 1 suspected skier accidental persistent slab occured, see avalanche description.

Skier crossing a alpine bowl feature triggered a slab at 2350m on a NW aspect. Trigger point was near a rocky outcrop, where ski pen increased (suspect due to facets around the rock). Suspected failure plane is March 14 FC and SH. Failure plane was down 45-55cm, with a 30cm 1F slab immediately above and 15-25 cm of HN over that. Slab cracked slowly underfoot, and spread 20m behind the skier. Lower down the slope, 2 other slabs released with the initial slab release. The other slabs were 250m in width, down 20-50cm. All debris arrested mid track, running 100-150m from their respective crowns. No skier involvement. Dialed it back to lower angle terrain out of immediate lees. Hand shears prior to the avalanche showed easy to hard planar and break shears down 45-55cm. FC and SH were observed on the shear surface. The results of this should have warranted a more in depth conversation do the destructive potential of the slab and risk involved with exposing the group to this peice of terrain. Good spacing and travel habits were used, but if the slope had released remotely above the skier, this could have been much worse. Photo shows trigger point on the left hand side of the upper most crown.