Gunnison
SnowpackZach Guy · Jan 28, 2012 · Gunnison
Weather
Morning temps near zero rose to 20F at 10,000 and 10F at ridgetop with light winds throughout the day primarily SW below treeline and ranging from SW-NW at ridgetop. Skies were clear.
Snowpack
Avalanche Obs: Control teams ventured into above treeline and near treeline terrain that we have left untouched since the round of storms that have impacted our area in the past two weeks. Above treeline on E to SE aspects, a 3lb hand shot in resulted in an HS-AE-R4D2-O, which failed in a fresh windslab ~30cm deep but stepped down into an old crust/facet/crust sandwich that formed in December. The slab was up to 140cm deep. Above treeline on SW to W aspects, explosives and ski cuts produced minimal results, with localized crossloaded fresh windslabs failing up to 20 cm deep. Near treeline on West aspects, we produced one SS-AB-R3D1-S, which failed in the most recent storm snow approximately 20 cm deep. On E to SE aspect of Ruby Mtn, we observed SS-AS-R2D2-I(maybe O?) which propagated an estimated 300 m wide and up to 1 m deep Snowpack Structure: ATL on SE aspects, a look at the crown showed 140 cm of rounded or DF grains above a 2cm meltfreeze crust above .5cm facets above a stout meltfreeze crust which acted as the bedsurface. On these aspects the slab depths and underlying snow structure are variable depending on windloading and degree of southerly aspect (more south facing terrain was completely dry prior to the recent storms). ATL on W to SW aspects the snowpack is generally shallow with <50 cm of settling powder above the ground (heavy wind erosion prior to and during storms), with the addition of crossloaded windslabs up to 20 cm from recent NW winds. In lower aprons, old faceted snow persists below a similar snowpack, but is not reactive to explosives or ski cuts, possibly due to lower slope angles or lacking of a significant load.