Bollettino valanghe

Eastside Region

Eastern Sierra Avalanche Center
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Pericolo valanghe

Mon
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato
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In sintesi

Moderate to heavy snowfall and strong winds out of the southwest will continue to load leeward start zones at all elevations. Large to very large natural avalanches are likely today. Avoid freshly loaded start zones and be wary of overhead hazards today. Traveling in and below avalanche terrain is not recommended.

Problemi valanghivi

  • Storm Slabs

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

    Periods of heavy snowfall are expected to continue throughout the day today leading to moderate accumulations. Storm instabilities, both slabs, and sluffs may continue to grow in size, becoming more sensitive as the day progresses. Avoid being on or under steep terrain over 30° today and be cognizant of your exposure to terrain features that increase the consequences of avalanches. This includes road cuts, gully features, cliff bands, and mid-slope depressions. 

    (3/10/2023)

    Slab avalanche in the Town of Mammoth Lakes

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2.5–4

    Deep persistent slabs are a difficult problem to assess, predict and manage. Deep slab instability likely peaked during Friday’s atmospheric river event when temperatures rose and precipitation rates were at their peak. While it is unlikely that a human will be enough to initiate failure on these buried persistent weak layers, a large wind slab avalanche may be just the large trigger that is needed to produce a very large and destructive avalanche. With good coverage in the tracks of avalanche paths at all elevations, these avalanches could reach maximum runouts and impact areas like mature forests and flat terrain usually considered to be safe zones. 

  • Wind Slabs

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

    Heavy snowfall and strong southwest winds continue to load leeward terrain features at all elevations. After many consecutive days of heavy precipitation and strong winds, wind slabs may vary in size and sensitivity. Remember, wind-transported snow can accumulate and overload the snowpack much more quickly than storm snow alone. Clues like blowing snow, textured snow surfaces, large fresh drifts, and hollow upside-down feeling snow can help you identify and avoid areas with recent wind deposits.  With good coverage at lower elevations, very large natural avalanches could run down to valley floors and into lower-angle terrain below treeline.  It's important to be wary of overhead hazards and avoid the runouts of large avalanche paths today.

    Wind slabs will vary in size and sensitivity today, but very large avalanches remain a concern in leeward catchment zones near and above treeline.

Avalanche Discussion

Strong winds continue to be the main driver of instability for the forecast area. Direct impacts of today’s unsettled weather are expected to vary across the forecast area and you can expect the distribution and size of fresh avalanche concerns to vary as well. Storm instabilities as well as larger more concerning wind slab deposits will be most concerning where snow totals are higher today. It is also worth considering that after such a massive winter atypical areas may pose an avalanche threat. Large drifts on exposed roof lines in town or large and steep snowbanks are areas to keep an eye on.

Keep in mind that this recent run of high-intensity storms has had serious impacts on communities, infrastructure, and road crews. Considerate travel choices and strategic parking will be appreciated if you decide to venture out today. With such 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.  Have a backup plan, 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 recently 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 finish the job.

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