Unintentionally triggered a size 1.5 avalanche today. Not really enough snow deposition at the toe to fully bury a person.

We'd been assessing surface snow conditions more or less continuously during our ascent. We dug various hand pits, stomped around in several locations, and noted snow quality and reactivity as we put in the skinner. We found no collapsing or cracking. I was surprised to see there was very little wind effect in the Bailey's zone. We did find chunky sluffing--the upper 2-3" of the snow surface was a bit cohesive, occasionally yielding small pieces that would break out underfoot that were F hard and maybe 15cm x 15cm x 5cm thick. In all our travels until this avalanche we were unable to get anything to move aside from point releases directly underfoot, sliding on the old snow surface (either firm wind affected or melt-freeze on wind affected).

Given the surface problems (i.e. lack of PWL concern) and soft snow that would break away beneath our feet (as opposed to above us), we elected to ski Bailey's. I cut the first pitch at the convexity with no result and proceeded down, stopping above the following convexity. My partner decsended without incident. Before proceeding, I mentioned aloud how steep the subsequent rollover was to our right (40+ degrees) and offered that I would go right, but my partner could go left on lower angle terrain and meet in the flats below if he preferred.

I dropped over the rollover on a left hand turn. As I expected potential dry loose, I cut right to get off the fall line and onto lower angle terrain (35-40 degrees). As I made the right hand turn, I saw a crack shoot out over my shoulder to my left. I continued a hard right traverse away from the avalanche. I radioed my partner to let him know I was alright and that he could ski to me on the bed surface.

The avalanche was a soft slab (F to F+ hard) composed of the new snow from the Thursday night storm and the Friday night storm. Crown was approx. 8-10" thick. Other size estimates are noted above. In addition to running on the firm old snow surface, there was graupel on the old snow surface that may have contributed to the avalanche. I was surprised to see sufficient connectivity for cracking that could generate a crown as we'd gotten no other indications of this throughout the rest of the day prior to that point. Best guess is that the angle was tipped up enough, the convexity was pronounced enough at a small enough point, and the graupel plus firm surface beneath all combined to permit a slab where I'd expected a sluff.

Apologies for the poor photo; that's the best we could muster with the flat light and low vis. Flank is visible in right side of photograph. Crown is angled uphill from the visible flank and emanated from a single point, running diagonally downhill either direction.