Detailed Observation

Date2021-02-22
LocationEastern Alaska Range
ObserverGrant Wilson
AvalancheN

General Observations

Total snow depth: 70cm

Snow profile:

  • 1-2cm faceted layer
  • 2-35cm unconsolidated “first seasons snow”
  • 35cm-55cm hard “pencil” wind slab
  • 55cm-70cm recent storm snow

We dug our pit on a 25 degree slope, below a small ridge that split two gully’s which we intended to ski. It was obvious there was loading in the gullys, which is why we dug our pit there.

Results: We found the wind slab at 35cm was highly reactive and failing before we could fully isolate a block to test. The unconsolidated “first seasons” snow (2-35cm) had enough compression to allow the 20cm slab (35-55cm) to be affected by a skiers weight. A final stomp above the snow pit confirmed how reactive the slab was… and our entire pit collapsed at 35cm. 

Even on such low angle slopes, we decided we were at a good place to turn around based on the obvious loading which continued above us. Combined with the recent storm snow, failure of the wind slab at 35-55cm could result in catastrophic failure on slopes  >25degrees. 

 

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