Wind Slabs on Andesite Ridge

25 to 30cm (10 to 12 in.) of recent snow rested on top of a crust in open areas on Andesite Peak this afternoon. In non-wind-loaded near and below treeline terrain ski cuts on small test slopes, general observations, and snowpit tests did not show signs of instability. There is a layer of loose snow just below the crust. Tests targeting this layer yielded the following results: ECTN 27, CTH 23 brk, and PST 40/100 SF.

In more exposed near and above treeline terrain, wind slabs existed on leeward slopes and fragile cornices loomed above these slopes. Ski kicks well away from the edge of small test slopes consistently caused cornice failure, but the oven-sized cornice pieces did not trigger wind slabs on the slopes below. On small wind loaded test slope where I could stomp on the actual wind slab, shooting cracks up to 3-4m (10 to 13 ft) occurred after a few hard stomps. A few more hard stomps caused the wind slab to separate and move downhill on the test slope. These stubborn wind slabs were about 30 to 35cm (12 to 14 in.) thick and relatively hard (4 finger+ to 1 finger hard). They failed on a softer (fist hard) layer of recent snow at the base of the wind slab (see photos). Light wind loading continued into the afternoon.