Bollettino valanghe

Eastside Region

Eastern Sierra Avalanche Center
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Pericolo valanghe

Fri
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
4 · Forte
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Additional new snow, extreme winds, and a weak underlying snowpack will continue to keep avalanche danger HIGH at all elevations. Travel in avalanche terrain is NOT recommended.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    1–3

    Extreme loading SW winds combined with upwards of another foot of fresh snow will produce fresh wind slab on NW-N-NE-E-SE aspects. This overnight storm in addition to residing fresh snow from the big storm this week provides plenty of available snow for winds to harvest and redistribute to leeward terrain. Zones adjacent to ridgeline, convex rolls and rock features will collect and build up fresh wind slab. Actively blowing snow and fat pillows of freshly deposited snow are sure signs of wind slab development. Avoid being on or underneath wind loaded slopes today as avalanches could be very large and run long distances. 

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    The old October & November snowpack residing on E-N-W aspects is weak and composed of faceted snow and temperature crusts. This rotten old snow at the base of the snowpack has been loaded with the big storm from Monday-Tuesday and then today's additional snowfall. We are now approaching a total of ~5feet of new snow with ~5inches of water equivalent that is weighting the weak snow below. We as Forecasters are particularly concerned about sheltered, forested Northerly-Easterly aspects from 9200ft to 10000ft where old snow sat for nearly a month rotting out. The direct correlation is that this terrain and conditions are found in THE SHERWINS which is one of the most popular and easily accessed backcountry areas in our forecast zone.  Check out yesterday's Punta Bardini Observation to get a good idea of what we are talking about. Persistent slab problems can be unpredictable and the tipping point of the weak snow failing could be the extra weight of snow today or potentially a skier trigger. This condition may heal over time, or we may have to deal with it for an extended period, but for now with the abrupt change to winter and rapid load of new snow this week, it will be good to give steep and complex terrain a wide berth where these potentially hazardous conditions reside.

Avalanche Discussion

With this abrupt change from autumn to full on winter in the matter of just a few days we as forecasters want to re-emphasize conservative decision-making as all of us adjust and get back into the rythmn of living and traveling in avalanche terrain. The large amount of new snow and weight, old underlying snowpack and extreme loading winds have changed the landscape dramatically and in quick fashion. It will be good to slowly work into less consequential and committing terrain with frequeunt check of the snow through snow pits, probing and observations to get a good idea of our newly formed snowpack. After the duldrums of November, we are certainly now on a great path to have a fun and snow filled winter. Remeber there's the whole season to look forward to.

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