Avalanche

Northern San Juan

Troy Nordquist Chris DicksonNorthern San Juan
Voir sur la carte
Photo d’observation 1Photo d’observation 2Photo d’observation 3Photo d’observation 4Photo d’observation 5Photo d’observation 6Photo d’observation 7Photo d’observation 8Photo d’observation 9Photo d’observation 10

Weather

The morning skies were clear with a cold temperature of 5 degrees F at the nearby Goldhill weather station. A little under 3 inches of new low-density snow, winds out of the Northeast were calm, and temperatures warmed to a high of 14 degrees F in the afternoon.

Snowpack

The snowpack here is simple and quite scary in its poor structure. It's composed of 4 layers: new snow since 12/28, sitting on a widespread knife-hard ice crust (the freezing rain event on 12/28), sitting over snow from the Christmas storm, above very weak fist-minus facets to the ground. The Holiday slab (everything that fell since Christmas) sits over the December drought layer, creating a textbook strong over weak snowpack structure and our current Persistent Slab avalanche problem. The most interesting piece of the puzzle is the 12/28 ice crust, which is unusual for our dry continental snowpack. It was hard to tell if the rumbling collapses were happening underneath this crust, or at the 12/25 weak layer. The ice crust in this area is 3mm thick and the grains under this crust are faceting.

Avalanche

As we traversed a 20-degree slope, we remotely triggered an avalanche from 900 feet away, crossing various terrain features and rocky outcrops. We had felt and heard several rumbling collapses along the way.