Vail & Summit County
AvalancheAustin DiVesta Andrew McWilliams · Apr 20, 2023 · Vail & Summit County
Weather
A return of winter-like temperatures and cold, dry snow. Moderate winds from the west-northwest along ridgelines
Snowpack
In the crown profile of the avalanche on Ptargiman Hill, we found 90cm of very hard snow in different states of the melt-freeze cycle. Some of this snow was knife-hard and difficult to shovel to dig the pit. This hard snow on top capped the bottom 54cm of snow, significantly softer at 4 Fingers on the hardness scale. These bottom 54cm were also moist. These melt-freeze crusts within the upper 90cm isolated the snowpack's bottom half, allowing this portion to become isothermic. Our Extended Column Tests produced one propagating result (ECTP 24 at 54cm), but we believe we accidentally cut the column. Our snow saws had difficulties cutting through the Knife hard layers. We repeated the tests and did not get any propagation (ECTX), suggesting that a significant trigger, like a piece of a cornice, triggered the avalanche.
Avalanche
Ptargiman Hill's south-east facing bowl below a large cornice and Shrine Bowl had an old Loose Wet avalanche which most likely ran around the 13/14 of April.