Date of Observation: 12/05/2022 Name: Zach Guy and Evan Ross
Zone: Northwest Mountains Route Description: Traveled on west facing terrain near and below treeline near Lake Irwin and east facing terran below treeline above Elk Creek.
Observed avalanche activity: Yes Avalanches: On west facing terrain at Irwin: We remotely triggered a small persistent slab from about 20 feet away (See video). The soft slab was up to 16″ thick, and failed on the topmost facet layer in stack of several facet/crust layers that were buried a week ago. The other steep slopes that we traveled near had all avalanched previously. Same for east facing terrain in Elk Creek: all of the paths that we approached slid naturally, probably during the Nov 29 storm. Weather: Overcast, light snow and graupel, moderate ridgeline winds with periods of light transport. Mild temps. Snowpack: Frequent collapsing and shooting cracks while breaking trail on west-facing terrain in the 20* to 30* range. The collapses are occurring on thin and weak facet crust sandwiches. Collapses were somewhat less common on east-facing terrain, perhaps because the slabs are thicker, but plenty of collapses nonetheless. There was an impressive amount of graupel in the top 10 cm of the snowpack. The slab continues to get stiffer and more supportive to skis, making for fun and fast skiing on low angle terrain. After clearly identifying that the terrain we were scouting had slid earlier in the week, we felt comfortable riding on those steeper pitches.
Photos:
Crown of remotely triggered slab
Profile on a slope that produced a large, slopewide collapse and shooting crack.
Profile on a slope that produced a large, slopewide collapse and shooting crack.
Don’t be distracted by Evan’s perfect skinning form. There’s a shooting crack in the foreground. West facing terrain NTL.
Shooting cracks, west facing terrain BTL
The crowns of previous avalanches are filled in, but we could see debris piled up against trees.
Relative Size: R1 very small Destructive Size: D1- Relatively harmless to people Avg. crown height (inches): 12 Avg. width (feet): 40 Avg. vertical run (feet):
Involvements
# of people caught: # of partial burials: # of full burials:
Relative Size: R2 small Destructive Size: D1.5 Avg. crown height (inches): Avg. width (feet): Avg. vertical run (feet):
Involvements
# of people caught: # of partial burials: # of full burials:
Additional comments: Way Long and Two Chutes, Irwin Westwall. Size and failure date is best estimate; crowns and debris have been subsequently covered by more snow and blown in.
Relative Size: R2 small Destructive Size: D1.5 Avg. crown height (inches): Avg. width (feet): Avg. vertical run (feet):
Involvements
# of people caught: # of partial burials: # of full burials:
Additional comments: Outer Limits, Irwin Westwall. Size and failure date is best estimate; crowns and debris have been subsequently covered by more snow and blown in.
Relative Size: R2 small Destructive Size: D1.5 Avg. crown height (inches): Avg. width (feet): Avg. vertical run (feet):
Involvements
# of people caught: # of partial burials: # of full burials:
Additional comments: Elk Creek, first two paths. Size and failure date is best estimate; crowns and debris have been subsequently covered by more snow.
