Bollettino valanghe

Eastside Region

Eastern Sierra Avalanche Center
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Pericolo valanghe

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

In sintesi

Though wind slabs have become harder to trigger, they remain a concern at higher elevations. Be careful around hard slabs. They may initially seem stable, but could break unexpectedly under a person's weight.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Recent slabs are layered over weaker snow in isolated areas and may be slow to gain strength. Hard drifts of hollow drum-like snow, or shooting cracks in textured surface snow are signs that may indicate unstable wind slabs. Be suspect of terrain features that encourage drifting, such as the leeward sides of ridgelines, alpine couloirs, gully features, and cross-loaded depressions. It may be possible to find small unstable slabs of wind-stiffened snow at lower elevations and in relatively sheltered terrain. Use extra caution around hard slabs, as they may be triggered from the bottom or sides of the slope, making them less predictable and harder to escape if caught.

    (2/22/2024) Photo: Samantha Rubin

Avalanche Discussion

Recent avalanche activity: Several large natural wind slab avalanches ran in the major avalanche paths on McGee during the recent wind loading event. Crowns faced north through east and were located just below ridgelines at approximately 10,000'.  The largest of these avalanches stepped down to the ground on a rocky SE facing sidewall in the mid-track resulting in a larger avalanche (D2.5).  No new avalanches were reported as having occurred yesterday.

Snowpack Summary: Variation in snowpack depth and strength between drainages continues to be a major theme this season. Around Mammoth Lakes and areas to the north, the snowpack is over 5 feet thick. Depth hoar from the early season is still identifiable in the bottom 20cm but has gained strength. In the southern portion of the forecast area, the snowpack is closer to three feet deep. While signs of instability have decreased in these areas, the basal weak layers still have poor structure. Stability tests indicate that these layers could re-emerge as a problem if a significant new snow load and very large triggers are introduced. 

Limited observations yesterday suggest that wind slabs have gained strength and will be difficult to trigger in most areas. However, weak re-faceted snow found below slabs on northerly slopes is a source of uncertainty. Keep in mind that variations in terrain can effect the likelihood of triggering an avalanche. It may be easier for a slab to release on slopes steeper than 35 degrees with convex features, or where slabs are poorly supported by the terrain below.

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