Northern San Juan
AvalancheJeff Davis · Dec 18, 2020 · Northern San Juan
Weather
Snowfall tapered by mid-morning. Winds were light and temperatures just creeping into the double digits.
Snowpack
7 inches of snow equaling 0.5 inches of SWE was measured at the Red Mountain Pass snow study plot this morning. In general, the snow was light, fluffy, deeper as I gained elevation, and fairly reactive at the new/old interface. Cracking and natural avalanches in the new snow was observed specifically on steeper slopes. I dug in the Riley Boy avalanche path above highway 550 on a southeast facing slope at 11,800 feet. The snowpack on this slope was under a meter deep and had a worrisome curst/facet combination lurking below the recent new and wind-loaded snow. Not so long ago many southerly slopes were bare or very shallow, but this has changed as multiple winter storms over the last week has dropped significant snowfall accompanied by strong winds to the area. Snowpack tests produced moderate failures on a layer of facets above a curst in both Compression and Extended Column tests.
Avalanche
Small loose and slab natural avalanches observed across the highway corridor. The most significant natural activity was in the Brooklyn's, a series of steep west and northwest facing gully's below-treeline.