Central Sierra Nevada

Problemi valanghivi

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Likely

  Dimensione

  1–2

  The sudden shift from colder snowy weather yesterday to warmer sunny weather today will cause the new snow to heat up quickly. The bonds holding the new snow together will melt and it will become a mess of wet cohesionless snow sitting on top of the older melt-freeze crusts. Sluffs of wet loose snow will be likely on steep slopes in many areas today. In the places where only a few inches of new snow exists, these wet loose avalanches should remain small since there is only a small amount of snow to entrain. In places like the Mt. Rose area where more than 6 inches of snow fell during the storm, these wet loose avalanches could be large enough to injure or even bury backcountry travelers. Wet loose avalanches would entrain all of the new snow. Their size depends on the terrain since they gather snow as they slide downhill. Long steep slopes can produce larger wet loose avalanches. Terrain traps like gullies, creekbeds, cliffs, etc. can also cause problems since they can make small avalanches have bigger consequences.

  Pay attention to the snow conditions as you travel today. Rapid warming will cause them to change quickly. Some signs of wet snow instability include pinwheels, rollerballs, wet sticky snow, and sluffs of wet loose snow. As soon as any signs of wet snow instabilities exist, it is time to find an aspect that has not warmed up yet or move to low angle slopes without steep slopes above. 

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Possible

  Dimensione

  1–2

  Shifting winds during the storm left some wind drifted snow in areas near ridgelines. In most places along the Sierra Crest, these drifts remain small and wind slabs do not exist since new snow accumulations remained limited. In some areas (like the Mt. Rose area and maybe a few spots on the Sierra Crest) where more snow fell some of these drifts may have grown large enough to be small wind slabs. For the most part, these should have started bonding to the snow below them, but triggering a wind slab may still remain possible in a few places today especially on wind-loaded slopes that receive sunshine. 

  Wind slabs may not be widespread, but they still warrant attention today. Look for drifted snow, wind pillows, or other signs of wind loading while traveling in the backcountry. If signs of wind loading exist, evaluate the area carefully to see if a problematic wind slab may still linger there and move through the area cautiously.