Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

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

Wind-loaded near and above treeline terrain still holds fragile cornices and slabs of wind drifted snow. People can still trigger wind slab avalanches in these areas. Triggering a deep slab avalanche is becoming unlikely but may not be impossible in some isolated near and below treeline terrain where old weak snow lurks below the storm snow. MODERATE avalanche danger exists at all elevations. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    Despite the decrease in wind, expect to find slabs of wind drifted snow and fragile cornices lingering on wind-loaded and cross-loaded NW-N-NE-E-SE aspects. These wind slabs should be slightly more difficult to trigger today, but some of them could still break several feet deep and could involve enough snow to bury a person or a car (D2-D3).

    Smooth pillows of wind drifted snow on a slope, scoured areas on the ridge above a slope, and cornices hanging over the slope can all indicate the presence of wind slabs. Identifying where unstable wind slabs may exist can help reduce your exposure to this avalanche problem. Areas sheltered from the winds will hold softer less wind-affected snow. 

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2

    Weak sugary snow still exists underneath 3 to 5 ft of new snow in some areas on near and below treeline NW-N-NE aspects. On Sunday parties reported whumpfing on this layer and one avalanche may have occurred on Powderhouse Peak. Since then, signs of instability have decreased and evidence now indicates that getting enough force through the upper snowpack to break this layer would be difficult. Triggering a deep slab avalanche may be unlikely at this point, but it is not impossible especially with a larger trigger like multiple people on the same slope or a large cornice failure or with a smaller trigger at just the right spot/trigger point on some isolated slope. If a deep slab avalanche were to occur it would be very large and entrain all of the recent snow. 

    Due to the consequences of an unlikely but not impossible deep slab avalanche and some degree of uncertainty around this problem, it still warrants careful consideration. Identify where this layer may exist by probing into the snowpack or digging a snowpit. Recent avalanches, whumpfing, or snowpack collapse can indicate that you have found an isolated area where the deep slab instability remains active. If you have any doubts about the potential for a deep slab, go ahead choose a different aspect or more conservative terrain. 

Avalanche Discussion

* A report came in of a skier triggered deep slab on 3/15 at Powderhouse Peak.

* Yesterday skier triggered avalanches were reported on Tallac and Incline Lake Peak. These were most likely wind slab on wind loaded N facing terrain on Tallac and cross-loaded SE facing terrain on Incline Lake Peak. Small new wind slabs also were reported on test slopes on Fireplug and Incline Lake Peak yesterday.

* Tests targetting the facet layer below the new snow on Elephants Back and on Incline Lake Peak indicated that triggering this layer would be difficult but that if it does break fractures may still be able to propagate along the layer.

* Observations show the storm snow continuing to consolidate.

Regions covered