Bollettino valanghe

Eastside Region

Eastern Sierra Avalanche Center
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Pericolo valanghe

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

In sintesi

A warm atmospheric river arrives by mid-afternoon, bringing rain up to high elevations and strong winds. As rain saturates the snowpack, wet avalanches will become possible. Be on the lookout for wet, sloppy surface snow, pinwheels, and rollerballs.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–1.5

    SW winds have increased ahead of an atmospheric river making its way into our forecast area. Wind slabs from last week's storm may still linger on NW-N-NE aspects, and old slabs may still be sensitive where they rest atop a layer of weak, sugary facets.  New snow may form drifts at our highest elevations as the storm increases in intensity into the afternoon.

    Surface textures like dunes and drifts indicate the wind has been at work. If the snow you are moving through quickly becomes deeper, stiffer, and more dense, you have found a wind slab. Cracks shooting out from your skis or board are a clear sign you have found a slab. 

    (12/24/2024)

    Shooting crack in wind stiffened snow

    Photo: Steve Mace

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    An atmospheric river will bring rain up to 9000' by mid-afternoon. This water will saturate the new snow from earlier this week. As surface snow melts and water percolates down to to the various crusts from earlier this season, it will become increasingly easy to trigger loose avalanches in this wet snow. These are most likely on steep slopes, will start out small, and can gain speed and size as they run downhill.

    Luckily this problem is easy to identify and manage through timing. Starting early and planning for an earlier exit before the bulk of the precipitation arrives mid-afternoon will allow you to be off of steep slopes before this problem is at its worst. If your skis or board is sinking farther into the surface than earlier in the day, it's likely time to get off the slope. Keep in mind that if the storm arrives sooner than forecasted, this can become a problem earlier in the day.

    Photo: Steve Mace

Avalanche Discussion

You asked for precipitation, and it's here! A new atmospheric river makes its way to our forecast area by mid-afternoon. The storm will hit the northern part of our forecast area first, making its way southward throughout the day. With snow lines rising to 9000', this new precipitation will start out as rain that will saturate the 2-18 inches of surface snow that fell on the 25th. While there was an initial opportunity for shedding during the last few days of warm temperatures and sunshine, expect there to be plenty of snow to peel off crusts from earlier in the month as it becomes saturated with rain. 

Expect the world you walk out into this morning to drastically shift by this evening. Precipitation is slated to begin at a modest rate by mid-afternoon, however both the avalanche danger and the precipitation rate will rise into the evening. There is some uncertainty in the timing of the storm: if it comes in sooner than forecasted, then expect these shifts earlier in the day. We can account for this uncertainty by increasing our margins for timing with options in our travel plans. Keep an observant eye on how the snowpack is reacting to rain throughout the day as well as changes in the weather. 

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