Gunnison
AvalancheCrested Butte Avalanche Center · Dec 27, 2013 · Gunnison
Snowpack
SNOWPACK OBS: 3 hand-shears in dense timber all showed excellent bonding of X-mas storm snow to older snow. Q3 sheers (broken & rough) failing in old snow below interface. HS 80-110cm, mostly 4F-/F+ w/ irregular tree bombs, easy pole handle penetration. Ski pen 15-20cm. At the top of 1st Bowl (ENE aspect ) opened into more of a clearing where the trees were protected from wind by ridge & still caked w/ snow. Surface hoar visible on top & then shooting cracks, stepped closer to edge of slope and shooting cracks propagated over the roll to release a 40 foot wide crown. Well developed 10mm SH visible on bed surface. Traversed further past old ski tracks in the bowl on edge of crown line and dug a quick hand pit. Q3 shears (same as skin track) on N Aspect with more wind exposure which had no buried SH & none on surface. 2nd bowl, continued poking along ridge & found same pattern. ENE Aspect SH was preserved ~35cm deep and shooting cracks/avalanches resulting. Old crown slightly filled in lay adjacent to skier triggered. It's my theory the skier triggered slides in Axtell 1/2 bowl Dec 24 were on this SH layer that only survived in a few protected open areas. It's highly reactive but very isolated to open glades that are wind sheltered. This is a real conundrum as the BTL snowpack is stable in dense timber (no SH, lots of tree-bombs creating dense irregular surface, crushing FCsf, and breaking up storm slab) but in more open glades the SH is a wild card. Saw this SH in Splains Gulch meadow (E) just before the storm.
Avalanche
2 x AS-SS-R1-D1.5? failed on 10mm SH from Dec ~19 pre-storm 30-35cm deep crown Couldn't see runout, triggered from flats above on edge of skin track. Propagation ~40-50 feet.