Natural avalanches in Evans Basin

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 12/21/2015
Name: Zach Guy
Subject: Natural avalanches in Evans Baisn
Aspect: East
Elevation: Below treeline

Avalanches: Observed two natural soft slab avalanches that likely ran last night on an east aspect below treeline in Evans Basin. SS-N-R2-D2-O and SS-Ny-R1-D1-O. Failed on 2-3mm depth hoar at the ground. Crown heights were up to 40cm thick, with the slab ranging from 4F at the bottom to F at the top. The larger of the two slides showed impressive propagation, roughly 300 feet wide wrapping around a terrain feature. Measured debris piles up to 6 feet deep. The second slide looked to be sympathetically triggered, 50 feet away, smaller in size.

Weather: Light snowfall with intermittent pulses of S3 through the day. Light winds. Scattered to overcast skies.

Snowpack: Traveled along a creekbed this morning with multiple collapses, shooting cracks up to 40 feet, and creek banks peeling off into the creek. 18″ deep (4F to F slab) over facet layer. Traveled up to the base of the Evan’s Basin slide, got 3 or 4 rumbling collapses that appeared to travel as far as 100 feet away, and numerous other small collapses. Similar snowpack.