October 28, 2017

Chugach State Park – Front Range – Powerline Valley – South Ship Lake Pass

Human triggered hard slab avalanche.  Early season Chugach State Park snowpack is extremely variable and weak with multiple weak layers and interfaces (basal facets and depth hoar, melt-freeze crusts, buried surface hoar and faceted layers).  Recent dense wind slabs have developed on top of these weak layers and interfaces.  Weak layers and interfaces are widespread, and proving reactive to human triggers.

Avalanche details

Trigger Foot Penetration Avalanche Type Hard Slab Aspect Southwest
Elevation 3600ft Slope Angle 34deg Crown Depth 12in
Width 600ft Length 350ft

Obvious signs of instability

Recent Avalanches? No Collapsing (Whumphing)? No Cracking (Shooting cracks)?  Yes


Active wind loading: wind slab developing over hard, slick melt-freeze crust (weak interface) and area of old exposed near-surface facets.

Snow surface

Highly variable: dense wind-packed, soft powder, hard melt-freeze.


Extremely variable.