Natural Persistent Slab Avalanche on Broken Glass

While out making observations today on Tamarack Peak, we found a naturally triggered persistent slab avalanche that failed sometime late during the storm cycle on Thursday evening/night.  The avalanche involved multiple gully features separated by rocks and small terrain features in complex terrain.  The avalanche propagated approximately 500' wide and ran downslope around 500'.  Additional snowfall partially covered up parts of the crown line and the avalanche debris.  We could still make out shooting cracks that continued off from the crown line that ran into less steep terrain that did not avalanche.  Horizontal crown lines and avalanches that wrap around terrain features are indicative and common with persistent slab avalanches.  We experienced widespread shooting cracks, whumpfing, and collapsing of the snowpack today along with unstable snowpack test results indicating that this persistent weak layer is still reactive.