Gunnison

Avalanche

Zach Guy and Evan Ross · Mar 7, 2025 · Gunnison

View on map
Observation photo 1Observation photo 2Observation photo 3Observation photo 4Observation photo 5Observation photo 6Observation photo 7Observation photo 8Observation photo 9Observation photo 10

Weather

There was about 6" of new snow on the skin track since a group went up there yesterday. About 50 cm of snow this week down to the 3/3 interface. cloud cover: broken; wind loading: previous; recent snowfall (cm): 50; snow avail for transport: moderate amounts

Snowpack

The 3/3 interface buried at the start of this week's storms is small grained facets (~.5 to 1 mm) on northerly aspects, capped by a thin crust on NE to ENE aspects, and a thicker crust on due E.  The ingredients for an avalanche seemed to require adequate slab formation at higher elevations from more snow and wind drifting, and slabs appeared to be less reactive where they formed over thicker crusts.  Wind-sheltered terrain below treeline produced non-propagating pit results and no signs of instability while targeting steep features, likely because the lack of well-developed slab.  We did see one natural storm slab in sheltered terrain that ran during the storm.  We also targeted a repeat offender slope to assess deep weak layers and got hard, propagating results on the Feb 8th facet layer down 110 cm, with larger depth hoar grains still lingering near the ground.  See profile. . A couple of small collapses on wind drifted features along ridgeline. Triggered one slab.

Avalanche

Two large soft slab avalanches ran in Wang Chung and 4th Bowl during the storm. These were slabs of new and drifted snow that likely failed on March 3 interface a couple feet deep. Yesterday, a skier triggered a similar avalanche in the Pencil while skiing across the top of the start zone, and today, we triggered one in Quill by stomping and pushing at a drifted feature from the ridgeline (See video). These avalanches are a hybrid of problems: wind-drifted storm snow over a faceted weak layer.