February 4, 2017


Front Range – Glen Alps (Ramp N aspects):

Obvious signs of instability:

  • Numerous natural persistent slab avalanches triggered by Monday-Tuesday wind event


  • Sunny, calm wind, temps from the upper teens at Glen Alps trailhead to lower 30s around 5000′ (extreme inversion)

Surface conditions:

  • Variable, wind-affected snow: mostly supportable windboard (breakable in thinner areas of snowpack), wind-packed powder in sheltered areas


Many wind loaded areas (primarily cross-loaded gully sidewalls) produced natural persistent slab avalanches during the Monday-Tuesday wind event (generally HS-N-D2-R2-O/G, but some larger).  We got a closeup of one larger slide that broke out along the cliffs around apron level in the area of the Ramp’s north couloirs.  The Monday-Tuesday wind event natural avalanche cycle triggered many similar avalanches, especially in the South Fork area (wide propagation of persistent slabs along rock walls around apron level of steep terrain).

This avalanche (HS-N-D3.5-R4-O/G) had wide propagation along the cliff base, and the crown was over 6′ in places: