Observation: NWAC Forecaster

Advanced Information

Weather Summary

Continued light snowfall, cold and calm to light winds from the S

Avalanche Observation Comments:

One very steep test slope yielded a 30cm deep soft slab in new snow. The slab literally just fell apart in the start zone and dribbled down the slope. Wind features (mini cornices, drifts, etc.) were predictably reactive but not easy to find in observed terrain.

Snowpack Observations

Up to 30cm F/F+ new snow over 12/24 interface. +40cm ski pen. Was reactive in places where there was a soft slab formed by light wind transport, but never propagated more than a short distance from skis.

Under new snow in wind loaded locations . . . 10-20cm thick1F wind slabs from 12/24 were observed to be unreactive.

A few 20-30cm layers of alternating 4F and 1F down to 12/22 MFcr which is <1cm thick and very fragile (total of 120cm to 12/22).

Probed 250cm down to 12/8 crust and 10cm more to early Dec crust. +300cm HS in nearly all locations NTL.

Small and large column tests yielded no significant results in observed areas. ECTN's and easy to moderate PC and RP and B with compression tests.

Photo of typical 20cm deep soft slab - too little cohesion to pick up slab chunk, would just fall apart in your hands

Avalanche Problems

Wherever the new snow had any wind effect there was a triggerable slab. In observed areas would be surprised to see a D2, would be more likely in ATL. Loose Dry is almost a concern, mostly from getting pushed into a treewell or other hollow feature below steep terrain and getting fully immersed.