Bulletin d’avalanche

Eastside Region

Eastern Sierra Avalanche Center
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Danger d’avalanche

Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

Dangerous and unusual avalanche conditions exist across the forecast area. Avalanches, both wet and dry, are likely at all elevations. Rain on snow, extreme winds, and fluctuating snowlines will make for rising hazard throughout the day. Dial back your terrain and choose low-angle slopes.  

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    The atmospheric river will continue to bring a mix of rain and snow to elevations close to 10,000 feet. This water will saturate the new snow from earlier this week, as well as the new snow falling during the day today. Fluctuating temperatures will make varying density snow layers throughout the new snow. As surface snow melts and water percolates down to the various crusts from earlier this season, it will become increasingly easy to trigger loose avalanches in this wet snow. These are most likely on steep slopes, will start out small, and can gain speed and size as they run downhill.

    With the amount of new snow during the day today, it is possible for a larger, drier avalanche gain mass and combine with these wet avalanches at mid and lower elevations. These slides will be particularly destructive. If the snow surface is wet, then it is a sign that these slides are on the menu. 

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    With up to 7 inches of snow since yesterday morning, we can expect up to 14 more inches of snow to fall by this evening. This will fall atop a series of snow surfaces, with facets on E-N-NW aspects. This new snow will form a slab atop weaker, older snow that can create slabs close to 2 feet thick. Combined with strong to extreme S/SW winds, expect these slabs to be larger in areas where the wind has deposited snow: on the leeward sides of ridges, mid-slope catchment zones on the walls of gullies and below convex rolls. With the change of precipitation type throughout the day, expect these to break in unusual ways, in lower elevation terrain, and wider than expected. These will be largest where there is the most precipitation in the northern part of our forecast area.

    Cracks shooting out from your skis or board are a clear sign you have found a slab.  Surface textures like dunes and drifts indicate the wind has been at work. While these can be firmer and stiffer, know that there still can be soft slabs that develop— these will be harder to recognize. If the snow you are moving through quickly becomes deeper, stiffer, and more dense, you have found a slab. 

    (12/24/2024)

    Shooting crack in wind stiffened snow

    Photo: Steve Mace

Avalanche Discussion

A wet, warm, stormy and sloppy Saturday is on the menu, as today is the main event in this pulse of the atmospheric river. We have a shallower snowpack than usual this time of year, with weak faceted snow on most E-N-NW aspects. An intense pulse of rain and snow can still create unusual, scary, and unpredictable conditions. We might not be certain how these avalanches will be distributed due to the vast difference in snowpack depth and surfaces across our large forecast area, but we can tell you one thing: today is the day to expect the unexpected. While our precipitation totals are lower than our neighbors to the north in Bridgeport and Tahoe, storms that teeter between rain and snow can create more dangerous avalanche conditions than precipitation totals depict. The full story: avalanches that break today will have the potential to be destructive and run into typically safe terrain. Danger and avalanche size will rise throughout the day. Impacts will be greatest where there is more precipitation in the northern part of our zone, and taper as you head south. 

Today is the day for a mindset shift. We've been high and dry during this drought: able to get into as big of terrain as we wanted as coverage and fitness allowed. Today we must take an enormous step back. Choosing low-angle conservative terrain, being mindful to avoid avalanche terrain above you, and truly considering if today is even a good day to head out are the take homes from this forecast. There are days when managing CONSIDERABLEdanger is relatively straightforward, with some nuances from experience. Today is NOT that day. Before heading out the door this morning, consider the world you're walking out into. Rain on snow, wet snow, extreme winds, and fluctuating temperatures can make for some unusual avalanches and truly challenging skiing and riding conditions. If you decide to venture out the door today,  be honest with yourself and your partners about your experience, your comfort, and your desires. And most importantly: keep things conservative, whatever that means to you, to be able to walk back in the door at the end of the day.

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