Central Sierra Nevada

Problèmes avalancheux

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  1–2

  New snow and a warm spring sunny day will cause loose wet avalanches to form as daytime warming occurs.  The majority of these loose wet instabilities will form on E-SE-S-SW-W aspects, but could also form on NW-N-NE aspects with the increased March sun angles.  Loose wet instabilities could involve part or all of the recent storm snow received and could range from small to large in size.  Roller balls and pinwheels on sun exposed slopes will be a sign that rapid warming is occurring and that larger loose wet avalanches could become possible.

  Monitor warming while traveling in the backcountry.  Snow surface conditions could change rapidly today with the warming temperatures and sunny skies.  Once the surface snow becomes wet and sticky, it's time to change aspects.  Even small loose wet avalanches have the potential for increased consequences where terrain traps or downslope hazards exist.     

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  1–2

  Monday showed minimal signs of wind slab development where observations were conducted.  Overnight, NE winds increased into the 30 to 40mph range with gusts to 60mph for up to a 7 hour period, mostly along the Sierra Crest.  Winds have since decreased and are expected to shift back to the SW today.  Some redistribution of snow is expected to have occurred overnight with these NE winds potentially forming new wind slabs on SE-S-SW-W-NW aspects in near and above treeline areas.  Rapid warming today from increasing temperatures and sun could weaken wind slabs that have recently formed on sun exposed terrain.

  Look for signs of previous wind transport such as snow surface scouring, new cornice formation, and wind pillows.  Areas of concern could include cross loaded gully features and complex above treeline terrain where new wind slabs may have formed.