Mt Emmons Avalanche Visit

CB Avalanche Center 2019-20 Observations

Location: Crested Butte Area
Date of Observation: 03/23/2020
Name: Evan Ross, Zach Kinler
Subject: Mt Emmons Avalanche Visit
Aspect: North East, East
Elevation: 11,800ft

Avalanches: This avalanche is estimated to have released on the morning of 3/22, during a period of intense wind-loading and a pulse of high precipitation rates. The subtle aspect changes along the crown varied from NE to E and the snowpack structure was notably different between those changes. The avalanche was small for the terrain (R1) and large in destructive size (D2), therefore capable of burying a person. We spend our time on the deepest section of crown. The crown in that area average 60cm and was up to 125cm tall. The avalanche failed on-top of two separate crusts. Those crusts were each 2cm thick with the upper being Pencil hard and the lower 1F hard. Where there was the most wind-loading the avalanche failed on the deeper crust, lower on the ridge where there was less wind-loading the avalanche failed on the upper crust. Both of those crusts had 1.5mm facets on top and 1 mm facets below. Those facets were not particularly weak and didn’t produce results in ECT or PST tests from two separate locations along the crown. On the more NE tilted portions of the crown, the crusts faded away, but a thin layer of small rounding facets could still be found. The slope angle near the crown averaged in the upper 30’s and rolled over steeper lower on the slope.

There were some cracks in lower angled sections of the slope above the crown. Though of interest, there were no shooting cracks past the flanks of the avalanche or lower in the bowl where the avalanche debris passed through and came to a rest. The flanks of the avalanche noticeably decreased lower on the slope and below the previous wind-loading.