Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

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

With clear skies and above-freezing temperatures at all elevations, wet snow instability is likely again today. Timing of travel and positioning within terrain are the keys to managing conditions. Avoid traveling below warming snow, especially in confined or cliffy areas.

Avalanche problems

  • Loose Wet

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

    Warm, sunny weather over the past week led to a widespread wet loose avalanche cycle. These avalanches have been reported on most aspects and at all elevations. Despite a better refreeze overnight and slightly cooler temperatures today these avalanches are still likely today, especially on sun-exposed slopes. Strong ridgetop winds may limit the warming of surface snow at upper elevations. Snow near rock outcroppings, cliff bands, and tight rocky couloirs may warm faster than on less featured slopes with deep and consistent snow cover. Wet snow, rollerballs and pinwheels, and increasing boot penetration are all signs of surface warming that indicate conditions are approaching the threshold for wet snow avalanching. It is good practice to avoid passing underneath steep sun-baked slopes, especially in confined or cliffy terrain that limits options to escape runouts and could concentrate debris flows.

    (4/11/2023)

    Small wet loose avalanches on an E aspect at 9000'. 4/11/23

  • Cornices

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

    Overhanging cornices had a good test from warming temperatures this week. Some have failed. While cornice fall is most likely along ridgelines near and above treeline, cornices overhang leeward slopes at all elevations. Cornices can fail without warning and they often break much further back from the edge than expected. Give yourself a wide berth if traveling along ridgelines, and be wary of traveling on slopes underneath large cornices.

    Cornice fall above the entrance to "Hole in the wall" in the Mammoth backcountry. 4/10/23

Avalanche Discussion

Despite a decrease in natural avalanche activity under partly cloudy skies, multiple wet loose avalanches were observed yesterday. These were mostly small, but a few newer large wet debris piles were visible from the highway along Wheeler Crest on E aspects.

The snowpack did not have a substantial refreeze below treeline again last night and there is some uncertainty with regard to the cumulative effect of liquid water (~72 hours) within the structure of the snowpack at low elevations.

A wet slab avalanche was reported below 8000' in Onion Valley (25 miles South of the forecast area).  It is worth bearing in mind that, though unlikely, with continued warming similar avalanches may occur within the forecast area. These are more likely at the lowest elevations where air temperatures have not fallen below freezing for successive nights.

 

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