Northern San Juan

Avalanche

Brandon Mathis · Feb 26, 2014 · Northern San Juan

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Weather

Mild and warm. Significant temperature gradients over previous several days. Ten degrees in Silverton at around 9 a.m. and at 1 p.m. it was approximately 35-40 degrees at 11,000 feet. Partly cloudy, with about 30% cloud coverage, often warm, brilliant sunshine in the late morning, early afternoon.

Snowpack

persistent slabs and wind loading on most aspects across zone. Several wind events during the previous week. Rapid warming that day.

Avalanche

11,370 feet– devising a plan to ski across a wind scoured 35 degree slope to reach a treeline shot, it was taken into consideration that the components of a slide were all likely present, but that it was an impression that the real danger was on the east facing slopes behind us, and not below us and below treeline on the N/NW aspect. The were at least two skier tracks descending skier's right of the slide path, and we discussed skier's left (Scarcity?) in order to get the best snow. With caution, skier 1 (snowboarder 1) traversed the shallow snow above the path at a slight angle and within 6-8 seconds noticed the character of the snow changing drastically. Noticing a large crown growing and deepening clearly to his left, an eerie feeling of weightlessness affiirmed that his was being carried by a slab that he had triggered by ski cutting across the slope as it shifted from convexity to concavity. Being a few feet from the edge of the slab, he was able to make a heelside turn and carve slightly left to drop off the edge of the slab at about 3-4 feet in height. He then completed his traverse to the trees and sat still. Skier 2 watched snowboarder 1 and confirmed that he was safe and called out for vocal contact. After a short time, he traversed to snowboarder 1 and they noticed a large fracture above the crown that could easily be considered hang fire, so the two descended with caution, stopping to examine the slide and debris. Near the runout, the elevation was about 9860, The slide ran approximately 1500 feet.