Gunnison

Snowpack

Zach Guy · Dec 21, 2012 · Gunnison

Weather

Clear skies all day. Strong inversions, with unseasonably warm temps at higher elevations. Snow at treeline had strongest surface warming effect, with snow becoming wet in the top several cm. Above treeline, light SW to W winds kept surface snow cooler, but became moist midday.

Snowpack

Widespread weak layers forming on the surface. At valley bottom, we observed large surface hoar (up to 3 cm!). On shaded or low angle slopes, diurnal near surface facets forming a weak layer several cm thick. Near treeline, we observed a 0.5 cm thick layer of radiation recrystallization forming above 3 -5 cm of meltfreeze crust. A profile on a crossloaded SE aspect above treeline (HS 160) showed a mostly right-side-up snowpack, ranging from F+ at the surface to 1F near the ground. A thin and spatially discontinuous layer of faceting snow (1mm, 4F hardness) sits above the talus ground. Stability tests showed poor shear quality, mixed propagation results, and hard initiation on this layer, with no other concerning weaknesses midpack. We skied steep south slopes with no signs of instability, except for several small, loose wet slides releasing naturally from below cliff bands (D1) Observed numerous slab avalanches that failed during the tail of Tuesday's storm. Several D3 slides above treeline on N and NE aspects (Purple, Hancock, Peeler), near and below treeline, numerous D2 and D1 slides (Schuykill, Coney's, etc).