Northern San Juan
SnowpackDomi Frideger · Dec 6, 2016 · Northern San Juan
Weather
There was light-medium snow through out the entire day. Temperatures were from 10-15 degrees Fahrenheit. According to CAIC, winds were 15-25 MPH with gusts of 40 MPH. The wind direction was WSW. There was extensive blowing snow and wind loading. We triggered a small D1 R1 avalanche at around 11,800 ft. on a NW facing shoot above Prospect Gulch.
Snowpack
Before we triggered the avalanche, we were well aware of the avalanche problems which were persistent slab and wind slab NW-E at and above treeline. In Prospect Gulch near treeline we found extensive wind loaded roll terrain. We did one column test in an area clearly that was clearly wind loaded. Our pit was 50 cm. deep and was facing due North. It was dug at 11,868 ft. The wind slab was 46 cm. tall and at the bottom of the pit was 4 cm. of large and well developed facets. The column failed after 5 wrist taps at the facet layer near the ground. After digging that pit, we proceeded with caution and triggered a crack on a wind loaded roll over on a N aspect that propagated about 20 ft. After safely approaching the shoot we intended to ski, which was NW facing and began at 11,800 ft. we did not notice any wind loading and skied our first lap without issue on the more north facing skiers left side of the shoot. We climbed up again for a second lap. On this lap, one of my partners dropped first venturing farther skiers right into the shoot to a more NW facing aspect. He turned heavily and triggered a very small avalanche with a crown 10 feet above him. The crown was only 2-3 inches tall and did not penetrate past a shallow wind deposited layer on the surface. My partner skied away without injury. He was never buried.