Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
Out of date — this forecast expired 7 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Snow surface melt leading to loose wet avalanche problems is expected again today at all elevations, mainly in areas of direct sun exposure. Most avalanches will be fairly small, but avalanches large enough to bury a person could occur. MODERATE avalanche danger exists at all elevations.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    The situation remains largely unchanged. Snow surface refreeze is expected to have occurred again last night due to radiational cooling under clear skies despite above freezing air temperatures. These same clear skies and well above freezing air temperatures at sunrise today will allow snow surface melt to occur quickly on E-SE-S-SW-W aspects. Fairly widespread loose wet avalanche problems are expected again today with avalanche size mostly at D1 with up to D2 possible. The still fairly low sun angle and shorter length of daylight hours this time of year are expected to keep problematic amounts of surface wet snow from forming today on NW-N-NE aspects. While increasing winds and some cloud cover this afternoon will slow the rate of late day melt on sunny slopes, unstable conditions will have already formed quickly during the morning hours.

    Areas around exposed rocks in direct sun is where the greatest amount of incoming solar radiation and snow surface heating will occur. Rollerballs are an indication that instability associated with loose wet avalanches is forming. Choose terrain wisely considering how consequences from otherwise small avalanches can be greatly exacerbated by involvement with trees, rocks, cliffs or terrain traps below.

    Photo: Recent loose wet avalanche debris. A normally inconsequential avalanche until you hit the trees. Cloud deck associated with the air temp inversion layer - colder air below, warm air above.

Avalanche Discussion

* Well above freezing air temperatures and surface wet snow in sun exposed areas was observed around the forecast area yesterday at elevations above the lower atmosphere inversion.

* Numerous small loose wet avalanches (size D1) have occurred around the forecast area over the past two days.

* The upper snowpack remains transitional in most areas with a thin surface melt-freeze layer on top of cold snow yet to be affected by melt. This structure transitions from frozen to wet and unstable quicker than a well established spring time melt-freeze snowpack.

Regions covered