Quick report
Per the problem #1 description above. At the top of right gulley a hardpack/ice surface was observed, It was typical Tuckerman winter surface which was very skiable but not enjoyable. About 1/3rd of the way down the slope, conditions instantly changed to ~12-18" of accumulated graupel (tiny ball bearings of snow/ice), which was not well bonded to the crust below. The sharp change in conditions appeared to be a wind loading affect which was driving unbonded snow down the slope until sufficiently shielded from the wind such that it could accumulate.
Weather
- Air Temp
- 20
- Cloud Cover
- obscured
- Wind Loading
- intense
- Rain Elevation
- 2000ft
- Recent Snowfall
- 15 cm
- Snow Avail For Transport
- large amounts
Both the weather and avy forecast for the day were accurate. We got into trouble when the falling snow turned from a reasonably well bonding heavy powder, into completely unbonding ball bearings.
Avalanche
After discovering the deep unadhered graupel accumulation we attempted to move off the fall line, which required a few turns. During the 2nd turn, the slide initiated, starting 2/3rds of the way up right gulley and coming to rest in the brush at the bottom of the run. The slide was approximately 18" deep when it initiated. One skier was caught in the slide and transported about 300 vertical ft before working to the edge of the slide by applying gentle pressure to non-sliding surface below with one ski that had not come off. If both skis had come of the skier would likely have been carried the entire length of the slide and been at serious risk of hitting rocks/trees in the runout zone. (other ski found among small trees). In hindsight - being on the mountain all day and watching the conditions deteriorate firsthand (west wind continuing to increase, temps continuing to drop and precipitation changing from bondable to ball bearings) should have resulted in abandoning our right gulley objective. Some options were discussed after the pinnacle gulley climb was complete but were dismissed: take escape hatch and hike down (hard to find given the poor visibility in the alpine garden), ski down the auto road (huge hike back to get our overnight gear from hermit lake), or hike down lions head winter (this was the right answer, but was not selected since the top 1/3rd of right gulley lulled us into a false sense of security).