Forecaster Observation - Noisy Basin, Swan Range

Seth and I rode into Noisy Basin in the Swan Range today. Our objectives were to observe the aftermath of the recent of wind event and to asses the impacts of the new load/slab formation on deeper weak layers in the snow pack.  The debris and wind signature on the snow surface was impressive. The surface was a combination of debris from trees, sastrugi, hard wind drifts, and eroded cornices.  Skiing conditions were poor due to the variable wind-blown surfaces.  Hard wind slabs extended quite a distance below the ridgelines but were variable in reactivity. On a northwest aspect at 6400 feet extended column tests resulted in fractures that propagated across the column with easy force (ECTP4). When we moved to a more northeasterly slope the pencil hard slab was a lot more stubborn (ECTN25).

In most areas we continue to find a weak structure in the mid and lower snow pack due to layers of weak, faceted snow about 2.5-3 feet from the surface, as well as, depth hoar developing near the ground. None of our tests produced results on these layers, but their presence should inspire conservative terrain selection, particularly now that a slab is added to the equation.

*Note- The snowpit profile for Noisy Knob NE should have a 45 degree aspect, but incorrectly shows 315.  Aspect was NE.