Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

When in doubt, use simple terrain with minimal overhead hazard to limit your exposure to deep persistent slab avalanches. Potential problem areas include steep, unsupported terrain features and areas with shallow trigger points. Rollerballs coming from rocky chutes are warning signs that wet loose avalanches are becoming a hazard. Move to shady aspects as the surface snow becomes wet. You can ride sheltered terrain to avoid triggering dense, old wind slabs. 

Avalanche problems

  • Deep Persistent Slabs

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

    A persistent weak layer of faceted snow was buried in late February. Many deep slab avalanches released on this layer in the past 72 hours during and after a powerful storm when the weak snowpack structure was rapidly loaded by intense snowfall and wind. During this period of quiet weather, triggering one of these deeper layers is becoming a low likelihood/high consequence scenario. Potential deep slab triggers may include other avalanches or cornice fall. This is particularly notable as the March sun fully hits ridgelines and warms the roots of cornices. Deep slabs can propagate widely, connecting multiple start zones and terrain features. With good coverage in the tracks of avalanche paths at all elevations, some of these avalanches have reached far down into runouts and impacted areas like mature forests and flat terrain. Deep slab release is hard to predict and the problem is difficult to assess and manage. Features of concern include shallow trigger points, steep complex terrain, convexities, and slopes with overhead hazards. Uncertainty is high and avalanches could be unsurvivable. Avoidance is the best way to manage the hazard. 

  • Loose Wet

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

    The strong March sun will hit solar aspects and ridgetops today. Temperatures will be a few degrees warmer and wet loose avalanches will be possible by midday. Watch for rollerballs and small sluffs on sunny slopes as the first sign that wet loose avalanches are becoming a hazard. Rocky chutes, vegetated slopes, and areas with shallow snow cover will be the most concerning, especially if temperatures rise above freezing in your area. Plan your day to be off of and out from under very steep sunny slopes if the surface snow thaws causing you to sink into deep wet snow. 

    (3/16/2023)

    Small to large avalanches on Mono Jim

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1–2.5

    Slabs that formed during and after the storm have become stubborn. The higher you climb, the more likely you are to find dense, rippled drifts that can still crack under your weight. Decreasing wind today means that you can’t look for blowing snow to point to the most dangerous slopes. Instead, look at the terrain and the snow surface. Be suspect of features that encourage drifting such as the leeward sides of corniced ridgelines, gully features, and cross-loaded depressions. Wind slabs will be textured and stiffer than the snow in sheltered terrain. That’s where you’ll find more consistent, softer riding.

    (3/7/2023)

    Intentionally triggered wind slab

Avalanche Discussion

Small wet loose avalanches and large cornices are the highlights of yesterday’s observations. On Wednesday, explosives triggered mostly size 2 wind and storm slabs during morning mitigation at ski resorts and on highways. Reports of giant avalanches continue to hit our inboxes. Very large and historic avalanches breaking on deeply buried layers of old faceted snow ran down to valley floors entraining tons of wet debris below the rain line. Deep slabs failed between 7800 and 11000 feet on southeast, east, and northerly aspects. 

The good news is that the most recent of these monsters ran during and just after the storm. As very large avalanches become less likely, remember that the consequences remain high. Signs of instability may not be obvious. Using conservative terrain choices to put a wide margin between yourself and concerning areas is the best strategy. Be wary of overhead hazards.

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. As you walk around mountain towns with dense snow piled on rooftops, be aware that roofalanches are possible as temperatures climb.

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