Southern San Juan
AvalancheGrady James · Jan 3, 2021 · Southern San Juan
Weather
Mild and calm morning with little to no breeze at 11k. Ball cap and sunglasses kind of day in the San Juans.
Snowpack
HS at 11K in gladed and meadow terrain ranges from 85-100cm. The Dec 11 interface generally sits 50cm down in these areas. Collapses and cracking when traveling on skis or machine are occurring at a depth near this PWL, although tests indicate the exact failure is likely on the November 23 interface, which was a warm, weak storm that only saw .5" of water before 2.5 weeks of high pressure (See Snowpilot). Tests highlighting 10/23 interface (50cm down): CT16 SC, ECTN19, PST 22/120 END down 50cm. ECT indicates the overlying slab lacks enough consolidation to reliably promote propagation in this specific spot, yet the PST more accurately represents the situation we have been witnessing. The do will bite... HS in old growth is approximately 45cm- half of that seen in glades and meadows. 85% of wood and stump was covered by this last storm but remains as the primary hazard in these areas. Another 18-24" would open this terrain. The Dec 11 PWL tends to lay 20-30cm below the surface in this terrain and is broken by the surrounding wood. Collapses were more localized and restricted by wood from being more widespread. A failure on this layer in the future would likely see a smaller slide on the R scale but the terrain has significant obstacles that would produce trauma if a skier were caught.
Avalanche
Natural on Grayrock peak from point release in minor chute leading into path 2 was likely caused by morning sun or rock fall. 20210102 around 11am NTL, E, L-N-R1-D1-O