November 4, 2017

Observations

Talkeetna Mountains – Hatcher Pass:

Route:

  • Hatch – 4600 – Gov – 4600 – Hatch

Obvious signs of instability (red flags):

  • Skier triggered avalanche (see details and video below)

Weather:

  • Partly cloudy becoming mostly cloudy with light wind and alpine temps in the mid 20s

Surface conditions:

  • Variable (listed in order of prominence): areas of melt-freeze on all aspects (widespread on south and west aspects, isolated on northerly aspects), recycled (faceted) powder (especially on sheltered northerly aspects), supportable wind-packed (especially exposed upper elevation terrain on northerly aspects), breakable wind-packed

Snowpack:

Government Peak snowpit, ~4700′, 356* N aspect, ~35* slope, ECTP22 Resistant Planar:

Small, skier-triggered avalanche on cross loaded NE aspect between April Bowl and Hatcher Pass road (HS-AS-D1-R1-O):

Stability Notes:

  • The slab and weak layers of skier triggered avalanche seems to be same layers of failure in Gov Peak snowpit test, with reactivity difference being the friction of bed surface (low friction melt-freeze crust where skier triggered avalanche occurred; higher friction 1F wind-packed on Government Peak north face).
  • This wind-packed slab layer was found in many areas on predominantly northerly aspects (generally cross-loaded terrain features) and was avoided as much as possible.