Professional Observation
Basic Information
Observation Details
Observation Date:
December 23, 2021Submitted:
December 23, 2021Observer:
Josh Feinberg | Key ObserverZone or Region:
Mammoth LakesLocation:
Sherwins - Mammoth Rock - Upside-Down New Snow, ECTPsSigns of Unstable Snow
Recent Avalanches?
None ObservedCracking?
IsolatedCollapsing?
None ExperiencedSnow Stability
Stability Rating:
Very PoorConfidence in Rating:
HighStability Trend:
WorseningKey Points
-Quick late afternoon jaunt up around Mammoth Rock, being careful to keep to mellow terrain and out from under the run-out of steep slopes above. I’ve seen debris from an avalanche at the ridge of Mammoth Rock Bowl make it down below 8,800′ below the depression below Mammoth Rock before, and it felt like a day that that could be possible. Made it to ~9,200′ before turning around.
-Found about 2 feet of fairly dense new snow with an upside-down structure.
-Had one significant shooting crack that went more than 20′ across the slope in terrain exposed to the wind just below Mammoth Rock.
-Dug two pits, one on a WNW aspect at 9,000′ and another on a NE aspect at 9,200′, and both revealed an upside-down structure to the new snow with ECT tests consistently propagating with easy to moderate force at multiple levels of density change in the new snow.
Advanced Information
Weather Summary
Cloud Cover:
Obscured
-Snowfall intensity increased around 4pm to >1inch an hour.
-Strong gusty winds, variable and erratic (more out of SW than other directions though). LOTS of snow being blown around.
-Temps: 3pm at 8,300’=33.5°F, 4p at 9,200’=~29°F.
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