Central Sierra Nevada

Lawinenprobleme

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Unlikely

  Größe

  1.5–2.5

  The snowpack is stubbornly maintaining relatively poor structure. Despite this lingering poor snowpack structure, eight days have passed since the last report of an avalanche that failed on faceted snow near the bottom of the snowpack. Five days have passed since the last reported snowpack collapse. Clearly, it has become harder to trigger an avalanche as the weaker faceted snow that lingers at the bottom of the snowpack slowly gains strength. It appears that enough time has passed that the weak layers in our snowpack have become dormant. The nagging doubt and uncertainty comes from snowpit test results that continue to indicate with sufficient frequency that while difficult to trigger, an avalanche might still occur. Any isolated avalanches that fail near ground level will easily be large enough to bury a person, maybe even break a tree or two. We sit in the realm of a low likelihood, high consequence event.

  The areas where poor snowpack structure is most prominent is across NW-N-NE aspects above about 8000' to 8500'.  In isolated areas, a snowpack structure conducive to this avalanche problem has also been observed on E aspects. Additionally, there are weak layers found within the top foot of the snowpack that mostly lack an overlying slab for now. Look for a layer of graupel/small surface hoar/facets near a sometimes faint crust in the upper portion of the snowpack.

  While you can generally travel through avalanche start zones without triggering an avalanche at this time, some amount of avalanche hazard remains and uncertainty needs to be accounted for. Given the current conditions, it's best to travel through terrain maintaining margins of safety that can manage a surprise, larger than expected avalanche. Exposing only one person at a time to avalanche terrain is the norm. Utilizing only true safe zones for regrouping near avalanche terrain and avoiding the use of marginal safe zones can minimize negative outcomes in the event of an unexpected avalanche. Discuss with your group - What will be the outcome if this slopes avalanches wider than expected and runs further than expected? Are we managing that possibility, or just telling ourselves that it won't happen?