Central Sierra Nevada

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1

  Above the rain/snow line around 8,500' or so, wind drifted new snow will have formed some new wind slabs. These new wind slabs composed of dense wet snow are expected to be fairly small and difficult to trigger. Expect to find these wind slabs in lee areas near and above treeline on NW-N-NE-E-SE aspects. Avalanche size is expected at D1 with the potential for an isolated size D2.

  Use clues such as cornices, wind pillows, and ridgetop wind scouring vs deposition to determine the areas where wind drifted snow has deposited as wind slabs. Account for how cliffs, rocks, trees, or terrain traps below could create injury or burial from what would otherwise be a small and inconsequential avalanche. The size and distribution of this avalanche problem are expected to increase over the next several days.

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1

  High elevation rain on snow has created the potential for a loose wet avalanche problem. Loose wet avalanches could occur just about anywhere today. Locations above 8,000', especially on NW-N-NE aspects held cold snow, unaffected by warming and rain prior to this warming event. These areas where rain is or has fallen on cold snow are particularly prone to loose wet avalanches. Avalanche size up to D2 is possible. Isolated natural loose wet avalanches are not impossible today.

  Roller balls are a sign of wet snow instability. Avoid traveling across or stopping below slopes where fresh roller balls are present.