Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
Out of date — this forecast expired 11 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

LOW avalanche danger is expected today for all elevations and aspects. Human triggered loose wet avalanches could still occur in isolated areas this afternoon on E-SE-S-SW aspects on slopes 37 degrees and steeper. Normal caution is advised.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1

    The snowpack on E-SE-S-SW aspects has for the most part adjusted to the post storm warming over the past 10 days. E aspects remain somewhat transitional in some areas while melt-freeze conditions have become well established on SE-S-SW aspects. Human triggered loose wet avalanche activity is expected to be more isolated today. This is due to cooler forecast air temperatures and the still relatively lower amounts of incoming solar radiation from the mid February sun.

    A decent snow surface refreeze is expected to have occurred last night, still driven mainly by radiational cooling under clear skies as air temperatures in most locations remained above freezing. This snow surface refreeze is expected to remain supportable through the morning hours today. Sometime during the mid day to afternoon hours conditions will become less supportable and loose wet snowpack instability will increase.

    Once body weight boot penetration approaches 1 foot deep or more into surface wet snow, change to a more northerly or westerly aspect and/or move to slopes less than 35 degrees in slope angle without steeper terrain above. Planned timing of travel in avalanche terrain is critical for the preferred mix of frozen to melting, but still supportable snow surface conditions.

Avalanche Discussion

Observations made yesterday on Tamarack Peak (Mount Rose area) and on Angora Peak (Desolation Wilderness area), both revealed that melt-freeze conditions have become fairly well established in the upper snowpack on SE-S-SW aspects. In some areas, E aspects lag a bit behind with a pockety mix of established melt-freeze and still transitional snow. Below 6,500' areas bare ground have started to appear as snow surface melt continues.

On shaded northerly aspects above 8,000' the snow surface has escaped undergoing melt-freeze with softer, colder snow lingering in wind protected areas. Below about 7,500' surface melt-freeze has created surface crusts on northerly aspects. Recent snowpit data from around the forecast area targeting the Jan 29 rain crust(s) in the upper portion of the snowpack have shown some minor near crust faceting, but no problematic weak layers at this time.

Regions covered