Report provided by party involved
My wife and I remotely triggered an avalanche in what we thought was relatively benign below-treeline terrain in the red cone zone (9676′ elevation, lat/long 37.60093, -119.02250). it propagated maybe 100 feet thru treed terrain across multiple terrain features with a crown depth ranging from 6″ to 2′. Our amateur analysis is that the super low-density snow that fell 12/27 was sheltered enough in this area to stick around and act as an extremely weak layer for the thick finger-hardness windslab that fractured and propagated like crazy. we didn’t go look at the crown or investigate further (sorry!) because we were so spooked by the extreme propagation and focused all our energy in getting out of there safe.