March 29, 2013

Eagle River – Outside Core Advisory Area

Signs of Instability:

  • Recent natural loose snow avalanches (sluffs) in steep terrain – likely occurred toward the tail end of the most recent storm
  • Mixed snowpit test results: snowpack quite variable within the couloir we climbed


  • We visited a relatively protected zone and winds were calm except when passing through one terrain feature with channeled winds that were light to moderate.  Winds were moderate to strong elsewhere in the advisory zone.
  • Mostly cloudy skies
  • Temperatures in the low to upper 20s decreasing with elevation gain
  • No precipitation

Avalanche Concerns:

We dug three quick snowpits with compression and shovel shear tests on our way up the couloir we climbed and dropped a large cornice into the couloir we skied.  Pole probing, hand digging, and our three snowpits revealed a quite variable snowpack within the couloir we climbed.  Mixed snowpit test results that were concerning had us on our toes and reasoning about our decisions through the climb considering the absence of more obvious red flags and our feeling about the variability and lack of energy in the snowpack.

The cornice drop into the couloir we skied made us feel confident in our decision to ski it as it revealed no slab avalanche problems and gave us a good idea of the loose snow avalanche activity (sluffing) that would be involved.

Our second snowpit @ ~4400′ provided a CTM(19)Q3 and CTH(21)Q3 on BIG depth hoar and facet chains on ground:


Our third snowpit @ ~4700′ NNE aspect revealed well over a foot of unconsolidated fresher snow on top of a layering of concern as seen in the middle of this snowpit:


This is the prominent, thin windboard layer as seen in the in the middle of the snowpit in the above photo:


It has this thin, weak layer of facets sitting between it and a pencil+ hard layer of rounds that had been faceting during the cold, clear period before the most recent storm.


Test results in the third pit at ~4700′ NNE aspect were an STE, STV, and three CTVs Q2 within the layering of concern mentioned above.  Although these test results had us on our toes, other signs and the fact that we were already committed led us to continue to the top.

We calved this large cornice off in halves to test the stability of this couloir we came to ski.  The second, bigger and harder half pulled out significant sluff from top to bottom, but no slab avalanche issues were revealed:    OLYMPUS DIGITAL CAMERA