Bulletin d’avalanche

Central Sierra Nevada

Sierra Avalanche Center
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Danger d’avalanche

Sun
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Recent strong winds have created slabs of dense windblown snow which may remain unstable.  Rapid warming may cause some minor wet snow instability today on slopes with sun exposure.  Consider avoiding slopes that sound or feel hollow underneath, have signs of instability such as snow surface cracking, or where rollerballs and pinwheels are present.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    Wind exposed terrain has been highly affected by recent winds over the last several days.  Gale force SW winds late Wed night into Thursday morning followed by two days of strong NE winds have left their mark.  A patchwork of rough wind scoured, dense wind slab, and firm icy surfaces exist near treeline and above treeline.  Unstable wind slabs may linger today in near and above treeline terrain on any aspect.

    Snow surface cracking may occur around the edges of these slabs, especially where they are thin. Thicker unstable hard slabs may not show cracking and may allow a person to travel far out onto the slab before an avalanche occurs. Hard slabs may feel or sound hollow underfoot. Wind exposed avalanche terrain that appears more filled in, smoother, and less scoured than surrounding areas remains suspect for human triggered avalanches today.  Consider avoiding any suspect terrain. Cornices along ridgetops are very large and should be given a wide safety margin.

    (1/19/2023)

    Skier triggered avalanche with two people caught and carried near Monument Peak, South Lake Tahoe, CA

    Photo: Public

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    A period of rapid warming today with light winds may create some areas of unstable surface wet snow on SE-S-SW aspects. Rollerballs and pinwheels are expected today as melting snow falls off of rocks and trees. Enough surface wet snow may form to allow for small loose wet avalanches to occur today as the snow surface enters its first melt-freeze cycle. This avalanche problem is most likely near sun exposed cliffs and rock outcroppings where increased heating occurs.

    Consider avoiding avalanche terrain where roller balls, pinwheels, or loose wet avalanches exist.

Avalanche Discussion

  • There were no reports of avalanches occurring on Friday.
  • Numerous avalanches were triggered by backcountry travelers on Thursday. Two people were caught and carried in an avalanche near Monument Peak in the South Lake Tahoe area.
  • Surface hoar buried 6 to 12 inches deep by the Wednesday night snowfall was unreactive on Friday in numerous observations around the forecast area specifically targeting this layer.  It is not impossible that an isolated area remains where buried surface hoar is an unstable weak layer in the upper snowpack.
  • Unconsolidated snow surface conditions remain in wind protected areas below treeline, especially on northerly aspects.

Régions couvertes