Central Sierra Nevada

Problèmes avalancheux

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  1–2

  Warming temperatures, strong April sunshine, and decreasing NE winds, will form unstable wet snow on all aspects and elevations as daytime warming occurs.  Wet loose instabilities in the form of roller balls and pinwheels will start to occur this morning on sun exposed slopes and then expand to other aspects with continued warming.  Many of these wet loose instabilities will be small in size, but some could entrain more of the recent storm snow and run longer distances in bigger terrain.  Even small wet loose avalanches could push backcountry users into terrain traps, such as cliffs, rocks, gullies, or trees.

  Roller balls, pinwheels, and sinking into boot-top deep wet snow can indicate that enough wet snow exists for wet loose avalanches to occur. Keep an eye out for changing conditions.  As the snow surface becomes wet and mushy, it's time to move away from avalanche terrain or change aspects to where colder snow exists.

  

• 

  Cornices

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  1–2

  Warm temperatures, strong sunshine, and decreasing winds, could lead to cornice collapses today.  These cornices have grown during our last storm cycle and exist on NW-N-NE-E-SE aspects along ridgelines.  The current NE winds have eroded and scoured some of these cornices, but many large cornices remain.  Cornice collapses could entrain recent storm snow or even an unlikely wind slab on a steep slope.

  Cornice collapses almost always surprise people. They fail farther back from the edge than expected and break wider than expected. If your route takes you along a corniced ridge, keep exposed rocks or trees between you and the cornice edge. Also, be wary of traveling on slopes under cornices. It's best to avoid these slopes, but if you have to travel on them, spend as little time as possible doing so.