Slabs of the Wind

CB Avalanche Center 2020-21 Observations

Date of Observation: 02/27/2021
Name: Jared Berman, Zach Guy Jack Caprio

 

Zone: Northwest Mountains
Location: East Bowl of Schuylkill Mountain
Aspect: North East, East
Elevation: 9,300′ – 11,100′

 

Avalanches: We intentionally triggered 3 small (D1) wind slabs on skis. Slabs ranged from 3″-6″ deep and were relatively harmless to a person. No recent naturals were observed today.
Weather: Weather started off overcast with light winds from the west below treeline. As we traveled clouds broke apart enough to see surrounding terrain and mountains. Moderate winds existed near treeline and we observed active wind transportation from some ridgetops and trees.
Snowpack: Persistent slab structure still exists on northeast aspects below treeline, capable of propagating deep failures. A snowpit at 9800′ on a northeast aspect revealed a 140cm hard slab (1 finger to pencil in hardness) resting on top of weak 2-3mm depth hoar at the ground (12/10 interface). The bottom of the slab contains rounding facets (1/19 interface) that appear to be gaining strength and were not as reactive as the 12/10 interface when comparing two propagation saw tests. See photo below of the snow profile with propagation saw test results.

Surface instabilities was a whole ‘nother ball game. Shallow wind slabs existed on isolated features near treeline and were reactive under skis. Slabs were small though ranging from 3″-6″ deep. We did not observe wind slab size or distribution above treeline as we did not travel at that elevation.

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