Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Avoid spending time underneath steep snowy slopes from late morning to late afternoon. In the southern portion of the forecast area, south of Mammoth Lakes, unconsolidated snow will get its first heavy dose of solar warming. Near summits and at the highest elevations watch out for unstable pockets of wind-drifted snow.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    In areas south of Mammoth Lakes, up to 6 inches of unconsolidated snow is layered over a hard slick old snow surface at all elevations. Temperatures will be warmer today with mostly sunny skies and decreasing winds.  Surface snow will become wet and prone to wet loose avalanches on most slopes, except steep, northerly terrain at the highest elevations.  Keep an eye out for early warning signs such as sticky and moist surface snow, upside-down feeling snow, and rollerballs & pinwheels. These are clues that may foreshadow larger point-release avalanches. Consequential areas of unstable snow are more likely in areas with higher snow accumulations from yesterday’s storm. A skier-triggered wet loose avalanche on Table Mountain yesterday is a good reminder not to underestimate the consequences of being involved in a wet loose avalanche.  Avoid travel in the runouts of steep snowy slopes that are being warmed by the sun. Be prepared to retreat to more shaded aspects if surface warming reaches concerning levels.

    Multiple small wet loose avlanches on an east aspect at 13,000'. 4/21/23.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    High-elevation north winds over the past 24 hours may have drifted recent low-density snow into sensitive slabs. Expect the size and distribution of fresh wind slabs to be greater in areas with higher snow totals. This problem will most likely be found above 11,500' in areas south of Mammoth Lakes.  Today winds are expected to continue out of the north at upper elevations with calmer winds near and below treeline. The presence or absence of blowing snow over summits and ridges will give a clue as to whether wind slabs are continuing to build today or are slowly gaining strength.  Large drifts, recent cornice growth, hollow upside-down feeling snow, and uneven snow surfaces are all clues that indicate nearby wind deposits. Do your own localized assessments and be on alert around terrain features that encourage drifting, such as the leeward sides of ridgelines, alpine couloirs, gully features, and cross-loaded depressions.

    (3/9/2024) Photo: Eastern Sierra Avalanche Center

Avalanche Discussion

Recent avalanche activity: Yesterday, a skier triggered, and was caught and carried by a small wet loose avalanche on an NE aspect below treeline on Table Mountain. This was part of a widespread cycle of loose snow avalanches near and below treeline in Bishop Creek yesterday. Multiple D1 natural dry loose avalanches followed moderate snowfall in the early morning, with wet loose instability rising as the day progressed. 

It is worth running through the past 48 hours of weather station data this morning to understand where our avalanche problems are most concerning today. In the past 48 hours, snowfall was concentrated south of Mammoth Lakes, with a gradient of snow from none in the northern drainages to up to 10" at the southern boundary of our forecast region. Up to 11,000' no slab development was reported, and no blowing snow was observed. Weather data from Mammoth suggests that strong north winds were present above treeline. Lack of upper elevation wind data from Bishop Creek (where there is plenty of snow available for transport) leaves a significant onus on the individual to make their own evaluation of wind slab hazard above treeline especially south of Mammoth Lakes.

The size and number of wet loose avalanches today depend on several factors. Snowpack factors such as recent unconsolidated snow over hard sliding surfaces in southern drainages, and weather factors such as the first sunny day following a snowstorm, and the high sun angle this time of year in southern California point to the potential for notable wet avalanche activity today. On the other hand mitigating factors include moderately cool temperatures for mid-March, the cooling influence of north winds at upper elevations, and the small amount of unconsolidated snow in most drainages within the region. The severity of the terrain you choose and where and when you choose to travel will control your exposure, and perception of the danger posed by wet snow instability today.

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