Central Sierra Nevada

Avalanche problems

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1

  Strong April sun and warm spring weather will cause loose wet instabilities today. Expect to trigger roller balls, pinwheels, and loose wet avalanches on steep slopes. Some small natural loose wet instabilities may occur on the most sun exposed slopes near rocks or trees as well. These loose wet instabilities could involve all of the new snow that fell on Thursday night and would likely slide on the melt-freeze crust below this snow. Most of these should remain relatively small since limited new snow exists in most places, but some could entrain enough snow to cause problems for backcountry travellers or injure a person. Loose wet avalanhces are possible today on any steep slope where new snow exists. 

  As soon as the sun hits the new snow today wet snow will start to form on the surface. Conditions can change quickly from cold soft snow to sunny warm unstable snow. Once the snow starts to feel wet and sticky or small signs of loose wet instabilities like small roller balls or pinwheels start to occur, it is time to find a colder aspect or head off the snow for a different afternoon activity.

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Unlikely

  Size

  1

  As the winds shifted from SW to W to NE over the last 24 hours, they also redistributed Thursday night's snow. Many N-NE-E aspects should be scoured back to the crust that existed prior to the storm but some may still have a few pockets of small wind slabs on them. Some small wind slabs may also exist on W-SW-S aspects near ridgelines. NW and SE aspects could have a mix of crusts and cross-loaded snow. While wind slab avalanches are unlikely in most areas, some small shallow human-triggered wind slabs may still be possible in isolated areas near ridgelines especially on sun-exposed slopes. 

  Clues like cornices above a slope, drifted snow, ripples in the snow surface, and other wind created features can help identify where these small isolated wind slabs may exist.