Northern San Juan

Avalanche

Ann Mellick Chris Bilbrey · Feb 8, 2022 · Northern San Juan

View on map

Weather

Sunny and warmer than recent days. Steady northerly wind above treeline.

Snowpack

We targeted northerly-facing slopes near and above treeline to evaluate volume of loose surface snow and sensitivity to trigger longer-running sluffs from added weight of a rider. We found 8 to 10 inches of weak, cohesionless snow consisting of faceted grains (1-1.5 mm) and remnants of last weeks snowfall that is also transitioning to near-surface facets. Loose snow sluffs were difficult to initiate today in steeper terrain at upper elevations, but the upper snowpack on shady slopes continues to weaken increasing depth of faceted snow by the day. This is most apparent once you climb above 11,000 feet. Ongoing surface faceting may increase a rider's chance to trigger a loose dry slide on lower-angled slopes versus isolated areas approaching 40 degrees in steepness. The faceted snow surface below treeline was unreactive when jumping on steep test slopes. We did not find any drum, hollow slabs in the alpine, but northwest winds helped to press the snow into soft, chalky surfaces several hundred feet below ridgelines and in cross-loaded terrain. The snowpack on sunny slopes in this area have begun to turn towards spring. Surface crusts range from 2-15 cm thick and are mostly supportive to a skier's weight. A quick snow profile at 10,000 feet on an ESE aspect (100 degrees) showed a shallow (80 cm) and warming snowpack with drainage channels established to the ground. Pit tests produced no failures and the main layer of concern exists at the interface of wet to dry grains.

Avalanche

We did not see any fresh slides, though did see remnants of a couple older ones. The most recent were two long-running loose dry slide (looked at least a week old) above treeline on a north facing slope. We also saw the impressive D3 (only one in the region this season) that ran in late December. This slide was very destructive with large timber down in the creek over a large expanse.