Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

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

Warming air temperatures today are expected to cause snow surface melt leading to a wet loose avalanche problem at all elevations. In above treeline and near treeline terrain where yesterday's new snow was drifted and deposited as wind slabs, some areas of unstable snow may linger. MODERATE avalanche danger exists for all elevations.

Avalanche problems

  • Loose Wet

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

    Air temperatures today are forecast to warm above freezing at all elevations. These warm temperatures combined with the stronger levels of incoming solar radiation this time of year are expected to warm and melt the surface of the recent new snow. A wet loose avalanche problem is expected to develop today on sun exposed slopes, mainly on E-SE-S-SW-W aspects. Avalanche size is expected at D1 to D2 depending on the length of vertical run and how much snow becomes entrained.

    Roller balls will be the precursor to wet loose avalanche activity today. Exercise caution on steep slopes where natural or human triggered roller balls are present or where any wet loose avalanches have occurred nearby. Account for how downslope hazards such as cliffs or terrain traps could magnify the consequences of even a small avalanche.

  • Wind Slabs

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

    Lingering areas of unstable snow are unlikely but not impossible today where the 3 to 4 inches of recent snowfall was drifted and deposited as slabs 1 to 2 feet thick by SW winds. These wind slabs formed above treeline and near treeline on NW-N-NE-E-SE aspects. Avalanche size could be up to D2.

    Smooth to slightly surface textured slopes below or adjacent to cornice features and wind pillows are where these wind slabs are most likely to exist. Identify these areas of concern, adjusting travel plans as necessary to manage risk.

Avalanche Discussion

* Signs of newly formed wind slabs were observed yesterday with snow surface cracking present in wind loaded areas.

* A variety of snow surfaces existed prior to yesterday's new snow including melt-freeze crust, rain crust, and rough wind-scoured surfaces. Expect to feel these firm surfaces under the recent new snow. 

* Snowpit observations have noted that faceting has started to weaken the snowpack around the buried Feb 19 rain crust in the upper portion of the snowpack on NW-N-NE aspects. New loading of this developing weak layer remains minimal at this time.

* Some existing cornices may weaken today with snow surface melt.

Regions covered