Northern San Juan
AvalancheColin Mitchell · Feb 22, 2021 · Northern San Juan
Weather
High thin clouds covered most of the sky, increasing through the afternoon. Radiation was strong, but breezy conditions helped keep the snow cool.
Snowpack
I traveled northwest and west aspects near treeline. Hs averaged around 145. I targeted thinner areas for my profiles. The snowpack structure is still quite concerning on northerly aspects. Well-developed depth hoar sits underneath a slab around 80 cm thick. ECT's propagated on 21 and 22 taps on this layer. Higher elevation NW slopes were thin and wind-hammered, but NTL there is plenty of volume and structure for skier triggered slides. Westerly aspects were more consolidated. A stout melt-freeze crust from our January dry spell sits above the facets here, making it harder to affect the weak layers. The basal facets and depth hoar are rounding and strengthening. ECTX and ECTN 22 on the depth hoar/slab interface. No sign of wind transport in this part of the range. Temperatures on the cool side and breezy conditions helped keep the snow cool, but crusts were forming on sun-exposed southerly and westerly aspects up to 12,500'. I had a good view of this part of the range including lots of southerly aspects, and only spotted a few D1 loose slides in the new snow.
Avalanche
A handful of small loose slides observed from steep, south-facing terrain, mainly above treeline.