Southern San Juan

Avalanche

Chris Bilbrey · Jan 6, 2019 · Southern San Juan

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Weather

Consistent snowfall during the tour with generally light winds below treeline. Snowfall rate varied between S1 and S2.

Snowpack

Recent storm snow was right-side-up and we measured 13" of snow with 1.3" SWE at 10,800 ft. Lots of cracking and collapsing observed on northeast to east, through southeast-facing slopes. Slopes near 35 degrees on side walls of gullys and convexities produced en echelon cracks while walking across the top. Small cornice that formed on several open slopes easily failed while approaching. ECTs produced non-propagating results in storm snow but produced an ECTP 18 on buried facets within top meter of snowpack. A thin melt-freeze crust existed on south and southeast aspects below storm snow with generally good bonding at old snow/ new snow interface.

Avalanche

Able to trigger a small soft slab avalanche at the top of an open 35 degree convexity below treeline. One jump onto the slope triggered the avalanche that ran approx 100 feet downslope. Avalanche failed on same persistent weak layer (facets) that produced propagating test result in ECT approx. 100 feet away in flat terrain on same aspect.