Gunnison

Avalanche

Ben Pritchett and Eric Murrow · Mar 5, 2020 · Gunnison

Weather

Hot and calm.

Snowpack

Full spring transition. Below treeline we found the water factory in full effect, with full-depth liquid water percolation in shallow faceted areas where there was no fine-grained snow to slow percolation. Shady surfaces were moist with no liquid water draining into the snowpack. On the shoulder aspects (east and west) we found stacks of crusts, with facets between above a mostly faceted base. Sweeping our hands in the loose facets between the crusts, we located frozen percolation tubes connecting crusts in many spots and never-wetted facets in others. Persistent Slab avalanches would be unlikely, but wet slabs would have been a possibility on certain features. We noted several meadow wide collapses later in the day with cracks running 10's to 100's of feet. The slopes we avoided had rilled surfaces. On deeper slopes (>~120cm) percolation was slowed draining thru fine-grained snow. We found several spots where water wicked beneath the slabs wetting the top of the facet layers. Near treeline the pattern was similar to the deeper below treeline spots, with liquid water mostly hanging up in the upper snowpack, wetting faceted weak layers in some places, but not continuously across slopes. Not quite wet slab conditions near treeline. Shady slopes near treeline were generally greater than 150cm deep, feeling strong and supportive. We got a half-dozen PST End results on facets with 35 to 40 over 100 cut lengths. One PST End later in the day went 25/100, a few meters away from one that went 35/100 two hours earlier. Above treeline wet snow was confined to steeper southerly slopes. Most surfaces were dry and wind textured.

Avalanche

Numerous small storm slabs from Sun/Mon storm. D1-1.5 Loose Wet avalanches in steep sunny alpine slopes that looked like they ran prior to today.