Observation: Turnagain

These are composite observations of the participants from today’s Alaska Avalanche School-Level Two
Refresher class.

Route:
Toured from the Sunburst lot to 3100ft, up the usual west ridge skin track, with a total of 6 people.

Weather:
Skies were partly cloudy with sun in the afternoon. Light winds in the valley floor at 10-15mph but calm
winds on the ridge above 2500′. Temps in the mid 20’s.

Signs of Instability:
No Whumphing or Collapsing.
No Shooting Cracks
No recent avalanches observed

Snow Surface Conditions:
Surface hoar 1-4mm is developing. It was observed from 1100ft to 3100ft. This new surface hoar is
sitting on supportable crust at lower elevation. This supportable crust begins to breakdown starting at
1500ft. From 1800ft to 2200ft were primarily wind scoured surfaces with pockets of soft snow. The
west ridge of Sunburst was wind hard wind scoured surface with anti-tracks very apparent from both
two and four legged travelers.

Snow Pack Observations:
5 test pits at 2500′, West Aspect, Slope Angles 27-30 degrees. Pit Depths 50cm-90cm.
Results: 4 pits at ECTX (no failure); 1 pit at ECTP15SC (sudden collapse of weak layer) @ 45 cm on
buried surface hoar (5mm) layer from December 11th and one finding of CT13RP (resistant planer) at
75cm on the Nov 18th crust layer with facets .

6 test pits at 3100′ on a SW aspect, Slope Angles 24-26 degrees. Pit Depths 135-150cm
Results: Primary findings were 6 pit results with ECTP 21-29 SP/SC (sudden planar/sudden
collapse) on the buried surface hoar (5-10mm) layer from Dec 11th at depths ranging from 35-50cm.

Secondary findings were 6 pits with ECTN 6-12RP (Resistant Planar) at 5-10cm, surface wind slab that
broke on a hardness change.

There are five lemons represented in the current snowpack because of the persistent weak layer of
buried surface hoar. 1) Weak layer in the top 100cm of snowpack. 2) Persistent grant type-surface hoar.
3) More then one step difference in hardness between layers depth hoar is fist softness and surrounding
layer are 1F to P. 4) Greater then 1mm difference between grain size, surface hoar is 4-10mm and
surrounding snow is 1-2mm and 5) Weak layer is less then 10cm thick.