Quick report
Communicating the current state of the weak snowpack is difficult. In general, a 2 foot thick cohesive snow slab sits atop weak sugary grains. This is confidently known. But determining finer details of the current snowpack (slab and weak layer properties sensitivity and distribution) is complex at best or just unanswerable. The difficulty is the uncertainty. Signs of snow instability may not be present, snowpack tests may or may not reveal instability, yet an overall weak snowpack structure is present. The possibility remains of triggering a large avalanche with high consequences. Persistent Slabs are particularly difficult to forecast; higher uncertainty brings a cautious mindset towards terrain and travel.
Weather
- Cloud Cover
- overcast
- Wind Loading
- light
- Recent Snowfall
- 10-15
- Snow Avail For Transport
- moderate amounts
Cloudy skies brought small amounts of snowfall (S-1) starting mid day. Calm with light ridgetop winds.
Snowpack
The long dry period in January formed weak sugary grains, the January Drought Layer (JDL), now buried 1.5 - 2 ft deep. We traveled through forested openings and dug a quick pit on a south aspect at 6400’. We found 10 - 15cm (4 - 6in) of new snow on top of older, firmer snow. The JDL at this location is 45cm (~1.5ft) down from the surface with a decomposing (breaking down) sun crust on top of the sugary faceted grains- the JDL. We observed Sudden Collapse test results on the JDL facets.
Continuing up to 7400’ ridgetop and digging on an E aspect, we found a similar weak snowpack structure. A total snowpack height of 250cm (~7.5ft) had 15cm (6in) of recent storm snow on the surface. We observed easy force Column Test (CT) results in the recent storm snow and dry loose on small rollovers. The recent snow and older firmer snow form a 50cm (~1.5ft) thick cohesive slab over a thin (0.5cm thick, P hard) crust sitting on top the JDL weak faceted grains. On top of this thin crust we observed Sudden Collapse CT’s and Propagating Extended Column Tests (CT14 SC, CT18 SC, ECTP20 (x2), all down 50cm from surface on the JDL). We also observed propagation to the end of column in 2 Propagation Saw Tests (PST 45/100 END down 51cm under thin crust on JDL and PST 35/100 END down 50cm above thin crust on JDL). Fragmented grains of buried surface hoar were found in this pit location below the thin crust and on top of the JDL.