We experienced whumpfing several times at about 6200' but nowhere else. Each time we climbed through this elevation we felt, heard and saw settling including shooting cracks and audible whumpfing. At this elevation in two isolated columns we had one failure on isolation and another on the 6th hand tap (which was lighter than typical hand tapping after the isolation failure). At the location we dug, there was about 25cm of wind delivered snow over a light crust over 5cm storm snow from March 6, over the March 6 crust. The failure was on top of the March 6 crust.