Northern San Juan
AvalancheKrista Beyer · Nov 29, 2024 · Northern San Juan
Weather
Negative six-degree temperatures in town gave way to seventeen-degree temperatures at the pass. Nearby weather stations show recent night lows below zero degrees around 11,000 feet. Winds were calm, and the blue sky and sunshine were abundant resources. The current forecast points towards more calm clear weather for the beginning of December.
Snowpack
Nearby weather stations show storm totals between 1.6 and 1.7 inches of snow water equivalent, corresponding to about 12 - 16 inches of snow. This new snow has since settled into a 10-14 inch slab of of fist hard over four finger hard snow. The layer of concern is the interface between the recent storm snow and the old snow that was present before the storm on November 25th. This November 25th layer consists of weak near-surface facets. Reports from the field suggest that this interface was very reactive during and shortly after the storm. As we near 48 hours from the storm's end, this interface appears to be gaining strength, and the slab above it is losing some cohesion. I received moderate non-propagating results in both east and northeast-facing pits. Moderate failures during compression tests yielded resistant planar results with slabs that broke apart easily. I dug the east-facing pit in an area sheltered from the wind. The northeast-facing pit was in an area with some leeward drifting and adjacent to an avalanche that failed naturally at the tail end of the storm. The crown line was an average of 35 cm deep, and the bed surface was a firm layer of wind-drifted snow. The surface of this wind-drifted snow is already beginning to break down.
Avalanche
Majority of avalanches observed on northerly aspects. All avalanches appeared to have failed near the end of the storm (morning of the 27th), and failed at the new/old interface.