Southern San Juan
AvalancheChris Bilbrey · Feb 23, 2020 · Southern San Juan
Weather
A mixture of overcast and broken skies. Intermittent light snow showers in the morning did not add up to measurable accumulations.
Snowpack
We found around 4 to 5 inches of new snow at pass level with up to 7 inches on leeward, near treeline slopes. Storm snow came in warm and wet to start and this promoted generally good bonding with the old snow surface. We observed lots of cracking in the new snow mostly along wind-exposed ridgelines and in larger open areas. Cracking was more pronounced where storm snow rest above an old snow surface that was a mixture of wind-packed snow with near-surface facets above (northeast-facing). Less instability observed where the old surface was a thicker layer of facets (north-facing). Wind-drifted pockets also had a thin 1 inch layer of 1F- snow above a generally 4F slab. It seems that a slightly thicker upper storm slab provided a little more slab cohesion to propagate cracks outward. We felt this would allow slabs to be more reactive in the alpine where winds had a bigger influence on slab stiffening. We easily kicked off loose snow sluffs in steeper, north-facing terrain near and below treeline that didn't entrain much snow while moving downhill. Sluffs were easy to manage, predictable, and generally harmless where we traveled. However, they could be more of a concern on longer slopes, around cliffs, or in gullies. Descending east and southeast aspects back to the highway showed good bonding with a firm melt-freeze crust below but new snow was warming up quickly with solar influence.
Avalanche
None observed today. Only minor sluffing of new snow above faceted old snow surface on slopes steeper than 35 degrees.