Southern San Juan
AvalancheChris Bilbrey · Feb 16, 2023 · Southern San Juan
Weather
Clear and cold. Steady north wind in the morning transporting snow onto leeward slopes, mostly above the treeline. Wind speeds decreased by midday reducing efficient snow transport.
Snowpack
Settled storm snow depths ranged from 65 to 80 cm across near and below treeline slopes. Ski penetration was around 30 cm and the lower half of storm slab layers were generally 1F- to 1F hardness. The quick settling of the new snow is promoting good bonding with the various old snow surfaces below and is helping compress the old faceted snow surface on shady slopes. We did not observe propagating failures in near-surface facets below the new snow in snowpits on northerly-facing slopes. The snow surface on north and northeast alpine slopes was moderately wind-pressed and steady winds easily drifted the low-density snow into soft slabs on east through south to southwest aspects. No cracking or collapsing on our travels. The snow surface on south-facing slopes below the treeline started to get thick by midday.
Avalanche
Evidence of debris flows across the landscape of many small to large Storm Slab avalanches - probably failing at the new/ old interface. These slides were on north to east-facing slopes above the treeline and likely ran mid-way during the storm. Most of the crowns were filled in, but debris piles were visible under several inches of snow.