Southern San Juan
AvalancheChris Bilbrey · Mar 18, 2023 · Southern San Juan
Weather
Cool, late-winter day. A steady breeze kept snow surfaces cool, even on due south-facing slopes. Clouds rolled in around 1 PM, and S1-2 snowfall got going around 1:30 PM. Maybe an inch or two of accumulation by the time we exited the mountains around 4 PM.
Snowpack
Warm temperatures and sunny skies on Friday formed a thick, robust crust on slopes facing east to south near and below treeline. At times, we could barley penetrate the crust enough to set a ski edge traveling uphill. There were mixed moments of boot packing, which revealed about 30 cm of softer, drier snow below. The crust thickness tapered as we climbed higher in elevation and also wasn't as brutal on southwest and west-facing slopes. Above about 11,800 feet, the snow surface on the same aspects was still softer and made for much easier travel conditions. We found a thin, breakable crust beneath the latest snowfall (between 20 to 30 cm deep) on southerly-facing slopes above 12,000 feet, with softer and beginning to facet snow below. This layer is shallow enough that the next round of storm snow has a better chance to overload this interface versus a deeper one. Overall, we found good bonding between the last two storms on most aspects and stiffer, drifted areas were stubborn to ski pressure. Slopes on the north half of the compass have a generally deep snowpack with fairly uniform layers near the surface. Even though the 2/14 PWLs has provided less evidence of lingering reactivity from recent storms, you can still feel that layer when probing across deeper areas.
Avalanche
Numerous Loose Dry avalanches above treeline on east, southeast, and south-facing slopes. These likely ran Friday and traveled into the near treeline elevation band. Very little loose activity originating near treeline. Below treeline on the same aspects, recent loose snow activity was wet. Spotted a couple of small to large storm slabs on easterly-facing slopes that likely ran during the last storm event. Also, 3 large natural avalanches on northeast and east-facing slopes above treeline that likely ran two storms ago - the first storm after the prolonged dry, windy period. These larger slides appeared to break above the hard interface and not stepping down into the 2/14 faceted interface.