Central Sierra Nevada

Problemas de aludes

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta montaña
  • Límite del bosque
  • Bajo el límite del bosque

  Probabilidad

  Likely

  Tamaño

  1

  New snow combined with strong to gale force SW winds will have drifted snow in near treeline and above treeline areas. This drifted snow will have deposited deeper and loaded mainly onto NW-N-NE-E-SE aspects. Unstable wind slabs are likely to have formed on slopes where this drifted snow has deposited. Avalanche size up to D2 is expected.

  Be wary of any slopes where small cornices or wind pillows have begun to form across the top. Stiffer snow on top of deeper softer snow as felt with the hand, foot, or pole should give pause for concern. Signs of recent avalanches and/or snow surface cracking are clear indications that unstable snow exists.

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta montaña
  • Límite del bosque
  • Bajo el límite del bosque

  Probabilidad

  Possible

  Tamaño

  2

  Weak old snow exists within the pre-storm snowpack and may become overloaded today and create a persistent slab avalanche problem. This type of avalanche problem is scary as it is less predictable. Persistent slab avalanches are often not triggered by the first person on a slope, can be triggered from the bottom of a slope, and can fracture well above, behind, or in front of a person. Basically increased uncertainty and much harder to manage than other avalanche problems. Any whumpfing (audible snowpack collapse), cracking, or signs of avalanches indicate unstable snow in the immediate area. Size D2 avalanches are expected.

  The weak layer for this avalanche problem does not exist in all areas. It has been seen on NW-N-NE aspects in below treeline to near treeline terrain above about 8,300' and gets weaker as elevation increases. This is fairly specific so making a plan to avoid it is not that hard. Other aspects or slopes less than 30 degrees in slope angle without steeper slopes above or adjacent are the go to places for avoidance of this avalanche problem. Use your inclinometer to measure slope angles. Guessing slope angles is not a repeatable strategy for success. 

• 

  Loose Dry

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta montaña
  • Límite del bosque
  • Bajo el límite del bosque

  Probabilidad

  Possible

  Tamaño

  1

  On wind protected slopes, instability within the new snow may allow for problematic storm slabs today. This will mainly be in areas near treeline to below treeline where a foot or more of new snow accumulates.

  If you encounter signs of instability such as snow surface cracking, recent avalanches, whumpfing, snowpack collapse, and/or unstable snowpit test results seek low angle (sub 30 degree) terrain without steeper slopes above or to the side.