Southern San Juan

Avalanche

Chris Bilbrey · Mar 16, 2020 · Southern San Juan

Weather

Warm and sunny. Light winds were felt along exposed ridges above about 10,500 feet and as we approached treeline. Snow surfaces got soft and moist up to about 11,600 feet then mostly dry above that.

Snowpack

Snowfall totals from last week seem fairly consistent with elevation between the north and south portions of the range. The most recent warmup is contributing to fast settlement in storm snow and diminished signs of instability. We found evidence of rain at the start of our last storm as high as 9,500 to 9,700 feet - saturated snow below the surface and lots of rollerball activity on steep, northerly-facing slopes. Snow surfaces warmed and softened up to around 11,500 feet on east and south-facing terrain but stayed mostly dry above that, except in wind-protected areas. Loose-wet activity after our most recent storm event was not as large and widespread as after the previous storm - this may be a product of better bonding between layers or the lack of a slippery sliding surface directly below. A snowpit on a northeast-facing slopes near treeline didn't yield propagating results in ECTs but a concerning weak structure was enough to avoid stiff, wind-drifted parts of the slope that would be more conducive to rider-triggering and slab propagation. All aspects below treeline are becoming more weak and rotten as we further transition toward Spring. As we slowly build surface slabs on below treeline slopes, the threat of Wet Slab avalanche problems slowly increases as a thicker, more cohesive slab forms above moist, weak large grain facets. Below 9,000 feet, the snowpack continues to melt out and the main hazard is trending more of a traumatic variety versus avalanches.

Avalanche

Lots of rollerball activity on SE, S, and SW slopes near treeline and from the base of cliffs in isolated alpine areas. Not the widespread shed cycle as observed on 3/13.