January 18, 2017


Turnagain Arm: Penguin

Obvious signs of instability:

  • D1.5 human triggered wind slab avalanche at 3800′ SSW aspect (ridge line)
  • A few distinct collapses (whumphs) between 2500-3000′
  • Short shooting cracks in deeper wind loaded areas


  • Sub-zero temps (-7*F)
  • Moderate NW wind
  • Partly cloudy skies

Surface conditions:

  • ~20″ very soft and light snow from trailhead to 3000′ in the west bowl (sheltered from wind)
  • Variable, wind-affected snow above 3000′ in the west bowl (1F rippled wind drifts & P exposed old wind slab)


  • Below 2000′: minimal to nonexistent base (~20″ recent snow with unsupportable, older faceted snow beneath)
  • Above 2000′: old wind slab, becoming more supportable with elevation gain, under ~20″ of new snow (collapses occurred between 2500′-3000′ where old wind slab was less supportable)
    • Varied persistent weak layers underlying old wind slab above 2000′ (primarily facets and depth hoar)