Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 11 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Avalanche danger is low for all aspects and elevations through the early morning hours.  As daytime warming occurs, avalanche danger will rise to Moderate on E-SE-S-SW-W aspects on slopes steeper than 35 degrees due to the possibility of loose wet avalanches.  Isolated loose wet instability may occur on some NW-N-NE aspects as well.

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1

    Snow surface conditions on solar aspects are going through a slow transition from recent storm snow towards an established melt freeze crust.  In many areas, the upper snowpack structure has several inches of wet surface snow on top of colder, more winter like snow below.  Overnight lows were above freezing at most locations above 8000'.  Temperatures are forecasted to increase today with lighter winds out of the SW.  Most of the loose wet avalanches expected today will be in the form of roller balls or pinwheels.  Although, larger loose wet avalanches are possible with enough snow to injure or bury a backcountry user.  The vast majority of instability is expected to occur on E-SE-S-SW-W aspects on slopes steeper than 35 degrees. Isolated instability may also occur on low to mid elevation NW-N-NE aspects

    Avoid solar aspects steeper than 35 degrees once the snow surface has more than a few inches of wet snow on top of the transitional recent storm snow.  Hand pits can be a quick and valuable tool to use to determine the structure of the upper snowpack.  Current roller balls and pinwheels indicate that the snow surface is loosing strength and that loose wet avalanches are possible.

Avalanche Discussion

Observations throughout the forecast area over the last few days show a transitioning snowpack.  On shaded northerly aspects, areas of unconsolidated snow exist with other areas of crusts, sticky snow, and wind scoured surface snow.  On solar aspects, the recent storm snow is transitioning towards a melt freeze crust.  In most areas, there are several inches of wet snow on top of colder dryer snow below.  The recent N-NE winds have helped to keep conditions cooler at the upper elevations and limit most loose wet instabilities.  No evidence of any significant wind transport has been observed with these N-NE winds.

On Lincoln Ridge (Yuba Pass area) surface snow was wet on southerly aspects but was mostly ski supportive at mid day.  Shaded northerly aspects was a mix of crusts, unconsolidated snow, and sticky heavy snow. 

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