Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

MODERATE avalanche danger exists today for WIND SLAB on Northerly-Easterly aspects. Southwesterly winds combined with plenty of light transportable snow from Thursday's storm will build sensitive slabs near ridgeline and in terrain conducive to capturing snow.  The area around Mammoth is of most concern where recent snow totals were the highest. Be on the lookout for blowing snow and fat looking pillows/drifts, and choose terrain wisely as even a small slide could be consequential with the plethora of bare ground and obstacles.

Avalanche problems

  • Wind Slabs

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

    Yesterday proved to be very calm and quiet with cold temperatures and little to no wind observed in the mountains. The new snow from Thursday's storm, which measures nearly a foot in areas around Mammoth, remained cold and light through out the day Friday and will be readily available for transport today.  Moderate to strong SW winds with gusts increasing to 45mph in the afternoon will start moving snow to the leeward Northerly and Easterly aspects, especially adajacent to ridgelines and in terrain such as cliff bands and gullies. Mammoth Mountain ski patrol produced some long running slides through explosive testing yesterday and previous natural soft slab avalanches from Thursday were observed in the Sherwins on N-NE aspects right adjacent to and near ridgeline.  Although most slides were D1 in nature, they could be enough to seriously injure a rider right now if dragged through the rock and exposed obstacles currently present.

Avalanche Discussion

Recent field observations continue to find weak and faceted old snow not only in sheltered mid elevations (9200-10000ft), but also in the upper alpine slopes on northerly-easterly aspects.  The light snow from Thursday and lack of recent wind has not yet produced much of a surface slab or dramatic hardness difference between the new and old snow. A majority of the backcountry snowpack, where there actually is coverage (N-E shady aspects), is quite loose such that one can post-hole all the way through to the ground when taking their skis off.  The upcoming storm could be just what we need to help fill in terrain and also clean out some of the residing old weak snow. We'll all have to stay cognizant of the potential for an upside-down snowpack if the old snow remains intact under heavy new snowfall.

Regions covered