Shattered

Storm day in the backcountry near Whitefish Mountain Resort. Strict travel protocols and sticking like bugs on flypaper to slopes not steep enough to slide let us check out some remarkably touchy conditions. We were mostly on mid-elevation, northeast to east-facing slopes. 

• Numerous small, shallow soft slab avalanches. Most triggered with slope cuts; a few triggered remotely, and a few small naturals. The slabs were 4-6" thick and broke at the interface between this morning's dense snow and lighter snow from earlier in the storm. Despite wide propagation, these were mostly harmless (D1-1.5) unless they carried a person into a treewell or other terrain trap. This same layer failed silly easy in tests - one tap. These slides were very slope-angle dependent - slabs cracked on slopes less than about ~32 degrees and slid on slopes steeper than that. 
• We felt a few muffled collapses, and another party reported remotely triggering several slabs that broke deeper in the snowpack, on old snow just below an eggshell crust. On investigating the crowns, we found they broke 50 cm below the surface and just below a thin crust, fragile crust. This layer collapsed and propagated in tests with moderate force, but did not always fail in ski cuts. The slab above this layer is soft (F-4F); as the slab stiffens, it may become more reactive. 
• Continuous moderate snowfall through the day (S1-2) with light winds. We heard a few gusts above us and felt some moderate winds at the resort summit, but observed no blowing snow. 

As the storm snow settles into stiffer slabs, the Storm Slab and Persistent Slab hazards may grow less touchy but produce larger avalanches.