Observation: Public

Observation Details

Signs of Unstable Snow

Observations

Traveled in the north basins on North Twin. Debris and crowns from very large natural avalanches that ran in early February still visible but filling back in. Several recent small dry loose sluffs in steep northerly terrain. Two (est. 48-72hrs old) natural slab avalanches in north-facing wind-loaded alpine terrain but shallow and small (D1.5). Blowing snow high in the alpine, but generally found 10-20cm of cold, low-density snow at the surface NTL and ATL with little wind effect. No signs of instability in the upper snowpack which was dense and right-side-up (4F-P hard). The mid-January PWL was found 150-200cm down from the surface. Stability tests targeting this layer did not produce concerning results (DTH ↓150cm BRK x2). The mid-January PWL appeared to be gaining strength and presented as 10cm of rounding facets (P hard) above the 20cm thick January 13 melt-freeze crust (K hard). Continuous snow began near 2000ft and the height of snow increased to 4 meters near 4000ft.