Sawatch
AvalancheJohn Mackinnon ยท Jan 5, 2015
Weather
OVC skies trending to SCT. Mild temperatures with above freezing temperatures observed above 11K. Moderate to strong west winds with moderate blowing snow at ridge-tops.
Snowpack
We observed several loud collapses and moderate shooting cracks on west aspects near and below treeline. BTL west facing slopes had mostly supportive and uniform snow (December/Jan. storm snow) on a weak faceted base. Ski pen was ~20-30 cm but boot pen was to the ground. HS averaged about 90 cm on the BTL slopes we visited. Near and above TL west aspects were more shallow and variable. NTL slopes had about 25 cm of hard wind slab overlying 35 cm of facets and depth hoar. Above TL slopes were a mix of crusts and bullet proof slabs. We dug several test profiles above the crown of a large hard slab avalanche above TL on an ESE slope. Snowpack structure was hard slabs overlying a facet/crust combo (Dec. 13th) about 10-15 cm above the ground. Below the FC/MFcr layer was 10-15 cm of DH. We go repeatable SC results in our compression tests on the FC/MFcr layer. Large column tests showed propagation potential as well--PST + x 1 and ECTP 21 x1 on the layer too.
Avalanche
Observed 3 avalanches today: one small wind slab that was within 48 hours old on a S aspect above TL; one small small persistent slab that had most likely occurred around xmas on an east aspect below TL; one large persistent slab that most likely ran after New Years. The large persistent slab occurred on an ESE aspect at treeline in the drainage north of question mark bowl. It ran on DH and to the ground in places. Good propagation and large blocks of debris. It took out some small trees.