Southern San Juan

Snowpack

Coal Bank pass. Pit: aspect- SE 120; elev- 11200; incline- 30; precip- s1; wind loading- yes; sky- obscured; wind- S (L). 50cm of high density storm snow sitting on a crust facet matrix 30-40cm from ground. There were 2 distinguishible crust with weak facets between and below. Base of the pack was 1mm facets showing signs of bonding. The bottom 10cm were 2mm facets, some of which are still retaining their cup shape; these were showing signs of bonding as well. Surface temp was -3.5C with a ground temp of 0.3C. Temps taken every 10cm revealed weak temperature gradients throughout the entire pack; no change greater than or equal to 1C / 10cm. Problem layer was the facets below the lower crust. Test results at this layer were CT13Q1, ECTP17 Q1/2, and PST 22/100 (End, 60cm down, 101220). Trail breaking was difficult with high density wind transported new snow. We experienced localized whoomphing on flat slope and on east 1/4 aspects. There was some minor cracking and whoomping while skiing slope 30 degrees and less. One crack propegated 10m and the slab popped but didn't move as one person traversed the top of a wind loaded gully moving to an island of safety; if the slope was steeper, we would have expected the slab to pull out. We observed some snowfall rates of S3 during periods throughout the day. Visibility was 100m so we stayed below treeline.