Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Moderate snowfall this morning and strong winds out of the southwest will continue to load leeward start zones near and above treeline. Large human-triggered avalanches remain likely. Periodic sunshine may add sensitivity to reactive slabs. Be on the lookout for signs of instability today and give yourself wide terrain margins to account for the potential for large avalanches.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–3

    Moderate snowfall and strong southwest winds continue to load leeward terrain features near and above treeline. Our current storm system is exiting to the south and higher accumulations can be expected near the Sierra crest and in the southern part of the forecast area today. Remember, wind-transported snow can accumulate and overload the snowpack much more quickly than storm snow alone. With winds continuing at transportable speeds today, you can expect continued slab development after the snowfall rates diminish. Clues like recent avalanches, blowing snow, and shooting cracks can help you identify and avoid areas of concern.   With good coverage at lower elevations, very large avalanches could run down to valley floors and into lower-angle below treeline terrain.  It's important to be wary of overhead hazards and limit your time in the runouts of large avalanche paths today.

    (3/20/2023)

    Large wind slab avalanches that caught riders by surprise in the Sherwins

  • Storm Slabs

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

    Storm instabilities, both slabs, and sluffs are expected to stabilize relatively quickly as precipitation rates decrease today. While natural activity will become less likely as the storm clears, human-triggered avalanches remain likely. Steep terrain over 30° in areas sheltered from the wind will be areas of concern today.  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.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2.5–4

    Deep Persistent slab avalanches failing within older layers of snow buried in February have become a low likelihood/high consequence scenario. While it is very 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 initiate a failure deeper in the snowpack. If triggered, expect deep slabs to propagate widely, connect multiple start zones and terrain features, and run long distances impacting areas like mature forests and flat terrain usually considered to be safe zones.

Avalanche Discussion

As our most recent round of heavy precipitation clears the region today it will be important not to let your guard down. After a long season with limited access and lots of snow shoveling, the promise of fresh snow can be a powerful draw. But remember that it will take time for the snowpack to adjust to this new load. Human-triggered avalanches remain likely today. We have received reports of at least 6 human-triggered avalanches in the past 48 hrs. Thankfully no injuries have been reported but there were some very near misses.   With such good coverage in the Sierra, we have a long season ahead. Patience and critical terrain choice remain crucial.

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.

Regions covered