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Avalanche: Little Superior

Observer Name
CO
Observation Date
Monday, March 21, 2022
Avalanche Date
Monday, March 21, 2022
Region
Salt Lake » Little Cottonwood Canyon » Little Superior
Location Name or Route
Little Superior
Elevation
10,200'
Aspect
Southeast
Trigger
Skier
Avalanche Type
Soft Slab
Avalanche Problem
Wind Drifted Snow
Depth
2.5'
Width
30'
Carried
1
Comments
Our party of 3 headed up from the Central Alta Trailhead sometime after 6 am, planning to ski south facing Little Superior at sunrise and approaching via the standard route. We left amidst the conga-line of headlamped humans heading toward Mt Superior (which we have mostly avoided on busier days for the last several years, for exactly that reason) We expected our primary snow problems for the day on the south facing aspects to be mostly manageable sluffing on the new/old snow interface and some pockety wind slabs. A bit of distraction and a momentary lapse in attention landed me right in the meats of one of those wind pockets. On the way up I mostly found that the 6"of new snow was fairly well bonded better to the old snow, better than expected, and on the ridge I made note of winds blowing out of the north, making our anticipated potential for wind slabs all the more likely. On the way up the last steep pitch up to Little Superior, walking on firm, wind scoured snow, we briefly discussed where to change over for the descent, and opted to quickly head around the corner; both to get out of the cold wind that was hitting us from the north, and get out of the way of the other groups skinning up shortly behind us. This over-attention to (or distraction by) the immediate discomfort from wind and crowds, led to overlooking the obvious wind pillow we were about to cross. Skinning along with one partner in front and the other behind, and stacking up a bit too close together in our hurry, I only really consciously noticed the wind pocket as I stepped onto it and the snow changed from firm and scoured to deeply loaded beneath my feet. I briefly paused thinking this was definitely loaded deep enough to be concerned, and I was way too close to my friend out front and should have given him more space as he crossed the wind loaded pocket... perhaps another second after this thought, my partner reached the thinner far edge of the slab, it collapse at his feet and the fracture propagated across and above me. I had about a half-second of high speed skin shuffling to try get off the top of the slab before it further broke apart, at which point I was in motion between the blocks, and one ski was pulled off. I quickly turned and punched both arms into the bed surface to self-arrest, and kicked in my free foot for added security as I tucked in close to the ground and let the rest of the slab pass over the top of me.
Well, that was stupid. I shook off the dust from my brisk snow bath, which perfectly to woke up the senses and brought sharp focus to our clear lapse in attention, a feeling of embarrassment for the dumb mistake, and a sigh of relief that it was a relatively small pocket on a soft enough bed surface to allow for self-arrest. We were caught by something that should have been obvious and easy to avoid, and we knew better than to stack up that close together right there. Given the terrain, it could have been much worse had things the set up been just a little bit different.
Looking at the crown, it was a new wind slab layered on top of an old wind slab, failing on a density change between the two. Roughly 2.5 feet deep at the thickest part of the slab (right where I had been when it triggered), and about 30 feet wide. The debris fanned out to only a few inches deep a couple hundred yards downslope, where I retrieved my lost ski before skiing down.
Coordinates