Northern San Juan
AvalancheJason Bushey · Dec 5, 2016 · Northern San Juan
Weather
SW to NW wind throughout day approx. 10-15mph with gusts up to 30-40 found at 12,600' all day.
Snowpack
Minimal observed ground facets on E aspects at and above treeline. Obvious previous loading with isolated small wind slab avalanches on E aspects on convexities. All slides did not propagate more than 3' and travelled minimal distance on 35 degree slopes. Avalanche was first sign of slab propagation. SE aspects had less snow with approx. 30cm of snow, to E aspects around 12,800 approx. 40-50cm. Obvious windloading observed with W faces at 12,800' completely bare from prior winds. No snow transport occurring during 12/3/16 but occurred from previous days.
Avalanche
Avalanche occurred at 12,330 on almost due east aspect on obvious convexity. Observed as R1D1 avalanche. Waypoint of avalanche linked here: https://www.gaiagps.com/datasummary/waypoint/66496404e419b2010262d6d24daf244d/?publickey=undefined&layer=GaiaTopoRasterFeet Avalanche occurred on windslab layer approx. 8-12cm thick, approx 40' wide, and 30' length. Lower layer was obviously stripped and then reloaded briefly. No pit tests were conducted on crown. Snow depth approx. 40-50cm. Images can be found on waypoint, and attached.