Quartz Hill Avalanche

Attempted to ski cut this convex roll, but did not see any results or shooting cracks. Upon skiing the convex roll, it avalanched a Size 1 Persistent Slab and propagated 20-25m with a 80-100cm crown line, ran about 5 metres before the slope angle prevented it from going further. Sunny, blue bird day with moderate winds in the morning increasing to strong towards noon, suspected culprit was the January 3rd SH layer, upon inspecting the bed surface, we found 3mm sized surface hoar. Top 10-20cm was F hard DF, 20-80cm was 4F with the last 20cm above the Bed Surface 1F hardness SH was also noted on the surface 1-2mm in size.