Northern San Juan

Avalanche

Ann Mellick Jeff Davis · Dec 15, 2021 · Northern San Juan

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Weather

We went out as storm #6 was winding down. Fierce winds and heavy snowfall brought a blizzard conditions to the mountains early this morning, but both the wind and snow were tapering by noon.

Snowpack

The snowpack received a heavy hit early this morning with a prolonged period of heavy snowfall combined with very strong south winds. Wind speeds averaged 50-60 mph and gusted in excess of 100 mph. Winds this strong often blow snow completely away. However, loading, and drifting could be seen on leeward slopes at all elevations. The snow below treeline is dense and wind abraded. We experienced lots of cracking and collapsing on shady slopes (easterly through northwesterly) failing on the ground and a crust that developed during the warming period on Sunday. A snowpit dug on an east aspect below treeline revealed a meter of firm slab sitting on large faceted grains. This slab failed easily in pit tests (ECTP4 and CT3). Spooky and highlighted todays elevated danger. A snowpit on a west-northwest aspect showed what looked to be a strong snowpack with around a meter of dense snow, but the slopes still collapsed when stepping out of skis. Snowpack tests did not produce propagating failures. A quick pit was dug on a north aspect below-treeline. On this slope a slab sat above well defined facets and snow columns would fail on isolation. This continues to highlight that north facing slopes that harbored old snow are definitely the most worrisome, but on slopes were there is a crust between the last two storms are also slopes to pay attention to as we could see avalanche breaking mid-pack.

Avalanche

We were able to see all elevations with good visibility by the early afternoon. We did not see widespread natural activity but we did see a handful of small avalanches on steep North and northeast facing slopes below-treeline. One a steep, repeat offender (Blue Point- east facing below treeline) and others were above the Long Fellow mine. Any slides that may have run early in the storm would easily be filled in and indiscernible after being filled in by the wind.