December 29, 2013

Sunday Observations – Arctic Valley

Signs of instability:

  • One significant, large collapse (not referring to it as a whumph – see below) in a wind-affected and loaded area, north aspect, where the snowpack is relatively deep a few hundred feet below ridge line


  • Light S-SE breeze with some short moderate gusts
  • Partly cloudy skies overhead, mostly cloudy skies elsewhere
  • Temps in the mid twenties

Surface conditions:

  • Variable, wind-affected snow ranging from lightly buffed powder, to soft and carve-able windboard, to breakable windboard, to fully supportable windboard (Randoman’s choice for skimo mini-golf)

Snowpack discussion:

In general, the snowpack throughout the Front Range and Eagle River area has poor, early season structure.  The strength of the snowpack varies from weak to strong depending on the area, terrain, and depth of snow.  While the structure is poor throughout the Front Range and Eagle River area and the strength varies, decreasing energy seems to be keeping avalanche activity in check.

With a short term forecast calling for quiescent weather with relatively warm mountain temperatures, snowpack structure and strength should improve marginally.  Along with decreasing energy, the likelihood of avalanches will decrease until the next significant weather event – whether it’s wind, snow, or both (dare we mention liquid precip).

Nonetheless, there was a sizable (large enough to bury, injure, or kill a person) human triggered avalanche reported off Peak 1212 (North Bowl) in the South Fork Eagle River area yesterday (Saturday, December 28, 2013) and we experienced a large and significant collapse in the Arctic Valley area today.  In support of decreasing energy, the aforementioned collapse experienced today was a peculiar groaning; an “old man whumph” if a whumph at all.  It was startling, but not as inherently unnerving as the typical “hormonally active teenager whumph.”  Both the skier triggered avalanche from Saturday and the large upper elevation collapse from Sunday indicate continued avalanche potential.  Worth mentioning, both these events occurred on northerly aspects which have been leeward (wind-loaded) lately.

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