Date: 03.24.18
 Location:  South of Copper Zone/Region:  Banner Summit
 Activity:   skiing
 Was it intentional?  no
 What type of avalanches?   Soft Slab
 What size?
 Size 1: Relatively harmless to people
 What Elevation?  8400
 What Aspect?   N, NW
 Comments: 1 foot deep, maybe 4-6 feet wide, NNW
 Comments: Skinned from main Copper pull out and observed light intermittent snowfall with moderate/heavy winds and gusts (South wind). Snow was visibly being transported by the wind. To investigate possible wind loading and wind slab, dug a snowpit leeward side of the ridge on a 25 degree north facing slope at 8750' (44.3280, -115.1970). Two potential weak layers were identified with a metal snow card, one about 1 foot down the second about 2.5 feet down. The top layer failed with two compression tests with 17 hits (10 wrist, 7 elbow) and testing afterwards the second weak layer failed around 20 hits (10 wrist, 10 elbow). These instabilities were construed as a windslab problem and elected to ski the protected and lower angle terrain below.

Skied first run down in more protected trees with no issues. At the bottom of the run, old large soft roller balls were visible in more open areas of the terrain (hypothesized from rain event last week). Skinned back up and noticed a short steep roll on the side of the run and elected to try on the way down. As the previously noted instabilities were only considered wind-related, increased avalanche risk here was not considered for the 40vert pitch. Skied into the run (this section averages 34 degrees) and went to the steeper pitch (45 degrees) on the side. Skied one turn to the left, felt a slight release and what felt like a little sluff. After skiing down and looking back up, saw that there had been a small slab avalanche on the 1 foot weak layer from the pit (approximate 44.3289, -115.1937). No one was caught by the slide, and there were no burial or injuries

Being in a protected area, the slide was hypothesized as storm slab from the Thursday snowfall (and possibly the night before). As the picture indicates, this micro-feature is much steeper than the surrounding terrain, which is probably why the main run showed no signs instability either from skiing or the nearby skin track.

Slide visible to left on the roll

Slide from below