February 21, 2017


North Fork Eagle River area:

Obvious signs of instability (red flags):

  • A few large collapses “whumphs” between 2500-3000′
  • Numerous recent, natural loose snow (“sluff”) avalanches from steep terrain


  • Clear, sunny skies filling in with high clouds and becoming overcast by evening
  • Generally calm wind; light down valley (katabatic) breeze in places
  • Alpine temps in the single digits; temps warming with incoming clouds by evening

Surface conditions:

  • Generally 25cm+ very light, low density powder with minimal to no wind effect


We experienced several large collapses, or whumphs, between 2500-3000′ while traveling along the valley floor.  While these whumphs were very large, they do seem to be exhibiting decreasing energy as compared to prior weeks.  We did not travel on terrain steeper than 35 degrees that had not already sluffed heavily.  We avoided open slopes capable of producing persistent slab avalanches.

Snowpit at ~5500′ on a northerly aspect showed a relatively homogenous snowpack that produced no stability test results (ECTX).  However, it’s important to note that the steep channeled terrain where we dug sluffs regularly and is less indicative of stability on moderately steep and open slopes.  Persistent slab problems due to basal weak layers and buried surface hoar are suspected on moderately steep terrain that has not already avalanched naturally.