Central Sierra Nevada

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2

  New snow and wind during the night allowed new wind slabs to form on wind-loaded and cross-loaded slopes that received snow instead of rain. These wind slabs will continue to grow as more snow and wind impact the forecast area today. While many of these wind slabs may remain relatively small, some of these slabs could measure 18 to 36 inches in depth in heavily wind loaded areas. These wind slabs may have a layer of lighter, colder, weaker snow that fell during the night at their base. Human triggered wind slabs will be possible today on wind loaded N-NE-E aspects and cross-loaded NW and SE aspects above 8000 ft. in near and above treeline terrain where more of the precipitation has fallen as snow. 

  As the second storm impacts the region tonight, wind slabs will quickly become large, and natural avalanche activity involving these large new wind slabs will be likely after midnight tonight.  Storm slab avalanches may also occur in non wind-loaded areas tonight due to the intense snowfall rates and changing conditions during the storm. 

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2

  Rain on snow may trigger more loose wet avalanche activity below 8000 ft. today. The NW-N-NE aspects will represent the best places to find loose wet snow avalanches since the snow on these aspects has not transitioned to corn snow, and it has not developed good drainage channels. Small loose wet snow instabilities like roller balls, pinwheels, and point releases should represent the majority of the loose wet snow problems today, but some larger loose wet snow avalanches may occur on those northerly aspects. Smaller more isolated loose wet snow instabilities may still form on isolated terrain features on the E-SE-S-SW-W aspects below 8000 ft.