Continental

Avalanche problems

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1.5–3

  Over the last 6 weeks, our area has seen mostly clear weather, interrupted by a couple of small storms that were quickly followed by strong winds. In addition to the lack of major storms, temperatures have remained well below seasonal norms and have only recently returned to average. This weather pattern has allowed the snowpack to settle, but it has also promoted faceting throughout the snowpack. This process has been most pronounced in the Continental zone, where temperatures were coldest and the snowpack was thinnest to begin with.

  There is not one clear persistent weak layer setup that users will find. Instead, conditions remain highly variable due to previous wind redistribution. In general, we are finding multiple layers of wind slab with facets in between layers of wind-affected snow. The depth and stiffness of these slabs varies significantly from place to place, so slope-by-slope assessment is recommended. Areas of potential instability may be identified by pole probing or digging to look for hard snow over weaker, softer snow. Keep in mind that conditions can vary widely, even across a single slope.

  A skier-triggered avalanche yesterday at around 4,000 feet on a west aspect near The Books is a clear reminder that instability is still lingering where stiffer snow overlies facets, despite very little meaningful weather change in recent weeks. Users can reduce their risk by practicing good travel habits, such as exposing only one person at a time to avalanche terrain, keeping a close eye on partners, and choosing simple terrain with clean runouts.

  

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  The sun continues to get higher in the sky, and daily high temperatures have slowly increased throughout the week. Wet loose and other solar-triggered avalanche activity has remained limited so far, but small wet loose avalanches have been observed on south through west aspects during the afternoon hours. Expect wet loose activity to increase as the season progresses. As warmer temperatures penetrate deeper into the snowpack, we are also concerned that faceted weak layers may lose strength and become more reactive.

  Watch for moistening surface snow, rollerballs, small loose avalanches, and failing cornices as slopes heat up throughout the day. If you begin to observe any of these signs, expect instability to increase with continued sun exposure.

  Please share any observed avalanche activity to help us track how this problem develops.

   

  

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Unlikely

  Size

  2–3

  Weak snow near the ground is increasingly common as you move North through our forecast zones, with the Continental zone being the most concerning. Although it still remains unlikely to trigger this layer, areas that have been scoured from strong northeast winds now have a shallower snowpack, making this layer closer to the surface and potentially easier for a rider to trigger.

  This is a low-likelihood but high-consequence problem most likely to be triggered in steep, rocky terrain and areas where the snowpack is thin or scoured. Triggering this layer directly is unlikely at this time, but avalanches that start in the upper snowpack could step down to the basal weak layer.  There is a high degree of uncertainty regarding the poor structure at the base of the snowpack.