While teaching an avalanche class we experienced two large whumphs with shooting cracks. The first was in a slightly north facing meadow at 9800' just west of Twin Lakes Pass. Our group of 5 had been doing companion rescue practice in the meadow for a couple hours when a second party skied through. The combined weight of 7 people was enough to collapse the PWL and we all felt the snow collapse under us.

A second large whumph occurred at 10,200' on the North Ridge of Patsy Marley. Our group was skinning close together on the main skin track, which dozens of people had used prior, when we felt another collapse and saw cracks shoot out ~100' onto the steep slope on the east side of the ridge. I'm shocked the slope didn't avalanche, but it somehow stayed in place. The cracks in the photo below extend another 50' out onto the slope