Gunnison

Avalanche

Zach Guy · Mar 16, 2014 · Gunnison

Snowpack

Light to moderate snow transport this morning, but most snow available for transport had blown its course by the afternoon. Localized cracking and slabbiness in drifted areas. Most terrain did not have loading, evidenced by old tracks or wet slides that were still visible at the surface, but isolated parts of slopes were loaded.

Avalanche

Investigated deep slab off of Owen from earlier this week. Crown depth was from less than a foot up to 12 feet deep, averaging between 8-10 feet. A dry slab, knife hardness. At the deepest point of the crown, there was still 8 feet of snow from the bed surface to the ground. Weak layers were virtually unrecognizable in the deep parts of the slab, but in shallower areas, there were 2mm, 1Finger hardness, dry facets above and below several crusts. We believe these crusts are the Jan 27 melt-freeze crust (which ended the 2-week high pressure system in January) and the Jan 29 Rain crust, which marked the start of the major February storm. In a few places we observed ice lenses from percolating water on the crusts, and we speculate those formed during January and not recently. The skier's left part of the slab failed on slope angles around 34 degrees on a south aspect, and the higher skier's right part of the slab was on slope angles between 45 and 55 degrees on SE and ESE aspects. There was evidence of gouging snow from ridge line to the high point of the crown and likely trigger point, probably from cornice fall, but it seems the cornice would have been fairly small. The debris piles on Green Lake are estimated 30 to 40 feet deep. The slide appeared to be large enough to destroy several buildings or a semi-truck. HS-NC-R3-D3.5-O Observed one snowmobile triggered windslab on a small East facing slope near treeline, 10-16" deep. SS-AM-R2-D1-I