Bulletin d’avalanche

Central Sierra Nevada

Sierra Avalanche Center
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Danger d’avalanche

Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 7 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Strong winds from both the SW and NE have drifted snow and deposited it as small unstable wind slabs on a variety of slopes above treeline and near treeline. Warming conditions today may allow for some minor wet snow instability on slopes in direct sun. MODERATE avalanche danger exists in wind exposed areas above treeline and near treeline with LOW avalanche danger below treeline.

Problèmes avalancheux

  • Wind Slabs

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

    Small unstable wind slabs have been present the past two days near treeline and above treeline from new snow and SW winds. A strong NE wind event occurred last night with plenty of snow available for drifting. Winds are back to SW today and increasing in speed so expect more drifting. At this point, slabs of wind drifted snow could be encountered on any aspect in near treeline to above treeline terrain. Expect a mix of scoured slopes and drift deposited wind slabs in adjacent areas. Avalanche size D1 is expected with size D2 possible in the most heavily wind drifted areas.

    Today will be all about identifying where wind slabs are present and moving cautiously around them. Identify wind slabs by looking for blowing and drifting snow, recent cornice and wind pillow formations, and areas of smooth looking slope. Snow surface cracking today is a sign of an unstable wind slab.

        Photos: D1 wind slabs from the past two days above treeline and near treeline.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    1

    Warming conditions today may allow for some minor loose wet snow instability in sun exposed areas, mainly on SE-S-SW aspects. Conditions along the northern portion of the Sierra Crest are most conducive to this instability today where a couple of inches or more of recent new snow exists.

    Exercise caution on or below steep slopes where roller balls and/or more than a couple of inches of wet surface snow are present. Expect increased snow surface warming near exposed rocks and in wind protected areas.

Avalanche Discussion

* Light snowfall events since Tuesday night have favored the Sierra Crest and deposited 5 to 6 inches over the northern portion of the forecast area and around an inch over the southern portion of the forecast area.

* Small reactive size D1 wind slab avalanches have been intentionally triggered over the past two days in the northern portion of the forecast area along the Sierra Crest in near treeline to above treeline terrain on N-NE-E aspects. Snowpack failure has been occurring on top of the Jan 4 rain crust.

* Weak snow in the upper snowpack (facets and low density DFs) around the Dec 12 and Jan 4 rain crusts are in a monitoring state for potential problems under anticipated storm conditions next week.

Régions couvertes