Northern San Juan
AvalancheAmy Pertuz · Apr 6, 2023 · Northern San Juan
Weather
Cold morning with a good overnight freeze kept surfaces well-frozen and cool into early afternoon. Light winds and bright sun., with ambient temperatures cresting freezing for a couple hours in the late afternoon
Snowpack
The upper 1.5 meters of the snowpack is fairly homogenous in this area, with snow depths ranging between 220 cm and 315 cm. Two crusts, formed in March, with associated facets at 40 cm and 55cm below the surface, show signs of strengthening. Though these layers produced clean shears in tests, the interface shows signs of sintering, and I could not get propagating results in an ECT. The wind/ temperature crust formed by the dust event Monday and Tuesday forms a supportable 1.5-2 inch thick layer which was resistant to ski or foot penetration on sunnier aspects and remained supportable on NE aspects where it is more of a wind-skin than a crust. Dry snow persists below the dust layer, and in the top meter of the snowpack. I saw very minimal loose wet activity in this area or much at all on the pass on Thursday. On east, south, and west aspects near treeline, the loose activity that was seen limited to the newest few inches sliding on top of this stout dust crust. On northeast aspects near treeline, the layer of concern is a thin layer of small facets buried about 30cm below the surface on top of a layer of stiffer, wind-drifted snow. Overall the snowpack here is fairly strong and homogenous.
Avalanche
Two avalanches from the March 22nd cycle