Northern San Juan

Snowpack

Susan Hale · Jan 20, 2012 · Southern San Juan

Weather

Partly cloudy to mostly sunny. Warm. Light southerly breeze. Comfortable day. (Quoting Mark..."now, what month is this?").

Snowpack

This area is generally ENE to NE and has multiple large benches above the main broad avalanche path that affects the road. We found lots of alternating moist snow surfaces to dry snow surfaces depending on the slope angle and slightest changes from ENE to NE. With all this variability we found a few common elements. First element is that the new snow has become a cohesive slab (4F to 4F+ hardness in the middle). This 22-25 cm thick slab cracks easily around skis, but we had to be on the colder NE aspects before we experienced collapse and some shooting cracks. The main weakness is - surprise, surprise - near the old and new snow interface. On the warmer ENE aspects the CT3&6 Q1&2 failures were (interestingly) within the new snow but only 1cm ABOVE a thin old MF crust (a little density change). Verified with a hand lens that these interfaces were stellar shapes (see pictures). On the more NE aspects, where the MF layer was missing, the failure was simply at the old/new interface. Underlying facets on all these slopes remain very weak and any slab aval activity will likely trench down into the facets to the ground.