Bollettino valanghe

Eastside Region

Eastern Sierra Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

New snow and a large wind event have left areas of unstable wind drifts around our region, and our buried weak layers may still be adjusting to these new loads. You're most likely to trigger an avalanche near the edges of wind-loaded slopes, and where the snowpack is generally shallower. Sticking to slopes less than 30º and without overhead hazards can help you avoid exposure today. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–3

    Our weak layers are still intact at varying depths throughout the region. In the Mammoth to June areas, the snowpack is generally deeper, and basal weak layers are 4 - 12 ft below the surface. In these areas, signs of instability may not be present. Finding a shallow trigger point, like shallowly burried rocks or bushes or convex rollovers, could trigger an avalanche involving the entirety of the snowpack, and would be, almost certainly, unsurvivable. In areas where the snowpack is generally shallower, 1 - 4 ft, we are still seeing signs of of instability, such as cracking and wumpfing, on buried depth hoar. These avalanches can be triggered remotely from slopes adjacent to, above and below. Sticking to slopes less than 30º with no overhead hazards is your safest bet to minimize exposure.

    (2/9/2024)

    Depth hoar grains from the base of our snowpack. Lakes basin, 10,400' NE 2/9/24

    Photo: Steve Mace

  • Wind Slabs

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

    Up to a foot of new snow fell during a significant wind event over the last 24 hours. We've observed numerous natural wind slabs at all elevations, up to size D2.5. Wind slabs ranging in size and sensitivity may exist on leeward slopes below ridgelines, in cross-loaded bowls, gullies, and in open areas below treeline.  Strong winds can distribute snow in surprising ways - don't be surprised to find isolated wind slabs below treeline. Cornices, stiff and hollow textured snow, and cracking are signs that can clue you into the problem. It is important to remember that in areas with a generally shallow snowpack, a small wind slab avalanche could step down to our buried weak layers and trigger an avalanche breaking near the ground. Make your own localized assessments and stick to lower angle, sheltered slopes to minimize your exposure. 

    (2/16/2024)

    Fresh wind slabs OBS 02/15 in Lakes Basin. 

    Photo: Samantha Rubin

Avalanche Discussion

In many ways we are dealing with two different snowpacks in our region. Mammoth to June has 4 - 12 ft of snow, and many other regions have 1 - 4 ft. These discrepencies in depth are causing layers to develop and heal in different ways and on different timelines. Where the snowpack is significantly deeper, we have intact depth hoar, but it is very difficult to trigger due to its depth. In shallower areas, depth hoar has shown significant signs of reactivity in response to loading, and has also shown that it can be inconsistent in where it lies. Due to the variability we are experiencing right now, exceptional localized assessments of terrain and conditions are essential if planning to travel in avalanche terrain.

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