Northern San Juan
SnowpackBill Nalli · Feb 11, 2020 · Northern San Juan
Weather
Clear sky and calm wind until 1:30pm. Clouds and precip to the south finally pushed north by 1:45pm. Just a trace of snow but clouds made for decreased visibility and very flat light.
Snowpack
Today's mission was searching for signs of persistent slabs and persistent weak layers on upper elevation northerly aspects and below treeline northwest through east. I found both, and also not both. Above treeline, some areas have been stripped and some have been loaded. Those that are deep are strong and those shallow (less than 130cm) are weak. The best theme I can find is something quite normal. Concave slopes and deep bowls are strong and in some places the pack is over 200cm. See snowprofile in Lena Basin. Convex slopes and those more exposed to strong winds are shallow and very weak. Our upper elevation persistent slab problem is specific to these shallow exposed slopes that now have a windslab over very weak snow. Below treeline a similar trend exists but much more of the terrain is shallow and weak. See snowprofile in Bear Creek. In the areas travelled today near Telluride I found less weekend storm snow and therefore less of a slab on top of this weak below treeline structure. The slab is not absent however as I did see one D2 on a NE aspect at 11,000 feet that failed at the end of the weekend storm. With higher snow totals in the Red Mountain Pass zone and parts east this hazard is slightly more ripe. You can still trigger avalanches where this structure is weakest. Watch for these two areas to become active again with the coming weekend storm. Many D1 wet loose slides were seen today on southeast through south at all elevations. Southwest likely did not have this problem as clouds rolled in by early afternoon.