Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Elevated avalanche conditions continue with wind slab, persistent slab, and loose wet avalanche problems.  Human triggered avalanches remain possible today.  MODERATE avalanche danger exists at all elevations.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1

    Strong to gale force NE winds are forecasted to continue through today.  Wind slabs will remain a problem on SE-S-SW-W-NW-N aspects in near and above treeline areas.  A skier triggered wind slab avalanche yesterday measured up to 3 feet deep in size.  These wind slabs are expected to remain reactive today.

    Look for blowing snow, wind scoured areas, wind pillows, and newer cornice formation to help identify what slopes are being wind loaded.  Solar radiation and additional warming may increase instability on these newly formed wind slabs.  Large cornices that were built out during the storm may become weaker with increased warming today. 

       Skier triggered D1 wind slab avalanche on Mt. Tallac.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2

    Concern continues for a persistent slab avalanche problem on NW-N-NE-E aspects at all elevations.  Avalanches have failed on the old snow surface crust which is now buried 1 to 3 feet deep below the snow surface.  Another potential persistent slab avalanche was skier triggered yesterday on Relay Peak in the Mt. Rose area.  Details are limited, but this avalanche does have some of the same characteristics of the other persistent slab avalanches.  Observations in other areas throughout the forecast region suggest that this layer has gained strength.  While this weak layer may be isolated throughout our area, pockets of instabilities still continue to exist. 

    Avalanches associated with this problem could be large, propagate wide, and be remotely triggered.  It is very difficult to know exactly where this weak layer exists and is problematic.  Avoidance is a repeatable backcountry strategy where you either don't go on the aspects of concern or stay under 30 degrees in steepness with no steeper connected terrain above or to the side.

      Skier triggered avalanche yesterday on Relay Peak.

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1

    Warm overnight temperatures with periods of sunshine today will allow for loose wet avalanches to form on all wind protected aspects and elevations.  Areas that receive light rain today will see an increase in loose wet avalanche activity.  While wind exposed areas should limit some of the warming today, loose wet avalanches could occur in wind protected higher elevation terrain.  Roller balls and pinwheels will be indications that larger loose wet avalanches could occur.  Loose wet avalanches could increase your risk of being pushed into rocks, trees, and over cliffs. 

Avalanche Discussion

A group of skiers were caught in a wind slab avalanche on Mt. Tallac in the North Bowl.  3 skiers were caught with 1 taking a ride for 500'.  The wind slab avalanche crown was up to 3 feet deep.

A skier accidentally triggered an avalanche on Relay Peak on a NE aspect around 9500'.  Another group responded to the avalanche and potential burial-with no one was injured.  This avalanche was reported as a wind slab, but it is thought that it could have been a persistent slab avalanche.  

Loose wet avalanche activity was reported from several locations throughout the forecast region. 

Regioni coperte