Boletín de aludes

Eastside Region

Eastern Sierra Avalanche Center
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Peligro de aludes

Sun
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Slabs that formed in the last forty-eight hours may still be sensitive to human-triggers. Local snow stability asessments could be challenging where buried weak layers are present under the most recent storm snow. Gather information carefully and maintain options for stepping back if signs of instability appear.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Blowing snow over the past forty-eight hours built winds slabs in terrain protected from west and southwest wind. Unstable slabs will most likely be found around terrain features that encourage drifting, such as the leeward sides of ridgelines, mid-slope rollovers, gully features, and cross-loaded depressions. Recent avalanche activity, cracking within the surface snow, recent cornice growth, and hollow upside-down feeling snow, are all clues that wind slabs may be unstable in your area. If triggered, avalanches could propagate widely, breaking above or around your skis, board or machine. 

    (3/24/2023)

    Recent natural avalanche in the Fingers on the Sherwins

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    In isolated areas, a reactive crust/facet combination exists at the new/old snow interface from 3/19/23. This layer is now buried up to two feet deep under recent snow from the past week's storms. Yesterday, upper snowpack weakness likely contributed to natural avalanche activity in Sherwins and the June backcountry. South of the forecast zone multiple human-triggered persistent slab avalanches were associated with this layer. Be careful of areas where the snow surface went through a melt-freeze cycle during the clear weather preceding this week's storms. Because this weak layer is in the top meter of the snowpack it is not a bad idea to track its presence and depth periodically throughout your tour by digging or probing. The most common warning signs have been collapsing and remote triggers. However, feedback may not be consistent and these avalanches could fail unexpectedly and in surprising ways. Be careful around wind-loaded terrain at mid-elevations, and in steep clearings and convexities below treeline.

    (3/24/2023)

    East Face of Tinemaha. Higher avalanche: D 1.5 wind slab triggered by a rider booting a ridge. East aspect, 12,400 ft. Lower avalanche: persistent slab remotely triggered by the same rider. East-northeast aspect 9100 ft. Rider caught and carried ~1000 vertical feet in the second slide and came away with minor injuries.

Avalanche Discussion

Snowpack discussion:

During a short window of clear weather between 3/16 and 3/18 a crust/facet combination developed at lower elevations (below 9500' ) at mid-elevation where the crust loses definition near-surface facets may still be present at the 3/19 new/old interface. In the past week two significant storms, one on 3/19 and one on 3/21 added up to 1-2 feet of recent snow over that interface.

The February Persistent Weak Layer is buried ~2m deep on a regional scale and avalanches on this layer are now unlikely. In isolated pieces of terrain a large natural trigger could still produce an avalanche breaking within old snow layers from the January / February dry spell.

Recent avalanche activity:

3/24/23 - Multiple Natural - D2 slabs released in the Mammoth and June Lake area. On at least one these crowns persistent grains were identified at the failure plane.

3/24/23 - Human-triggered - D2  peristent slab avalanche at 9100' on an ENE aspect in the Split Mountain drainage (south of the forecast zone).  One rider caught and carried. Party self rescued.

3/23/23 - Remote triggered D2 on an E aspect at 8000' in the Split Drainage / Red Lake area (south of the forecast zone).

3/21/23 - Natural-D3- Deep Slab, E aspect, 11300' on Mt. Wood

Comments:

Our winter full of high-intensity storms continues to have major impacts on communities, infrastructure, and road crews. Considerate travel choices and strategic parking will be appreciated if you decide to venture out today. With good coverage at lower elevations this winter, recent avalanches have been running further, impacting roadways and buildings in the communities of Virginia lakes, Mono City, June Lake, and Aspendell. It is important to practice good run-out awareness. Triggering an avalanche above infrastructure could have devastating consequences.  Remember that it often takes multiple passes to clear roadways and trailhead parking. Road crews are working overtime to allow access to communities that have been stranded by heavy snow, avalanche activity, and flood damage. Blocking snow drifts, travel routes, and snow piles makes it impossible for road crews to continue their work.

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