Ongoing persistent instability at site of Dec 24th Andesite Pk avalanches.

Location Name: 
Andesite Peak
Region: 
Donner Summit Area
Date and time of observation: 
Mon, 12/26/2016 - 10:10
Location Map: 
United States
39° 21' 4.194" N, 120° 21' 56.9412" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Obvious avalanche path
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Spent some time today examining the sites of the Dec 24th avalanches on Andesite Peak. At the site of the higher elevation avalanche (ENE 068 deg aspect, near treeline terrain, 34 to 36 degree slope angle, 8,120', previously reported here), snowpit tests in the crown indicated that instability was ongoing. The weak layer is a F hard layer of near crust facets on top of the Dec 15 rain crust, sitting under a F to 4F hard slab of new and old snow. This appeared to be the failure layer in the avalanche. Repeatable ECTP results in the 18 to 23 tap range pointed to the ongoing potential for human triggered avalanches in this snowpack. See video.

A handpit at the site of the lower elevation Andesite Peak avalanche that also occurred on Dec 24th  (NE aspect, below treeline terrain, 40 degree slope angle, 7,800', previously reported here) revealed a similar snowpack structure at both avalanche sites.

Snowpit videos (tests, etc): 

20161226 Andesite Avlanche Crown