Bollettino valanghe

Banner Summit

Sawtooth Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Wet loose avalanches could release naturally on steep slopes that directly face the sun and on all steep slopes at lower and middle elevations. Triggering a slab avalanche large enough to bury a person would require a dose of bad luck but remains a possibility on shady middle and upper elevation slopes that did not slide during the earthquake. 

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Today's intense sunshine and warm temperatures will melt the surface snow, making wet loose avalanches possible. These slides can occur naturally, without a human trigger. Where the snowpack is thin (near rocks and less than about 2 feet thick), some wet loose avalanches could gouge down to the ground. Where is this problem most likely?

    1. On steep, upper elevation slopes that directly face the sun: NE-E-SE aspects in the morning, S-SW aspects near noon, and SW-W-NW facing slopes later in the afternoon.
    2. On lower and middle elevation slopes with relatively recent, soft snow at the surface, regardless of the direction they face.

    Keep an eye on the condition of the snow surface while you're traveling. When it gets wet or when you see wet snow rolling downhill, it is time to move to gentle terrain or slopes where the snow surface is colder and drier. Wet loose instabilities can develop rapidly; think minutes rather than hours. Minimize the time you spend below all large, steep slopes that directly face the sun. 

    ADDITIONAL DISCUSSION: Weak layers of snow buried 2-3 feet deep have proven to be less reactive in this zone than in neighboring areas. On Friday, Chris went looking for this problem north of the highway. He found it in some of his snowpits but not in others. On an east-facing slope, he found a thin layer of facets on top of a crust, all buried beneath a 3-foot thick slab. The block did not fail during standard loading tests in his snowpack tests, but he was able to get it to break cleanly by applying some extra force.

    Dealing with persistent weak layers is tricky business, particularly as they become more deeply buried. Snowpack test results become more difficult to interpret and obvious signs of instability are absent. The first clear sign of an unstable snowpack may occur when you trigger a large avalanche. These types of slides can be triggered remotely—from a distance above, below, or to the side of a steeper slope.

Avalanche Discussion

In this zone, little snow has fallen since the earthquake rattled the hills and cleaned last week's storm snow from many steep slopes. You're most likely to find trouble on slopes that still have the 2-3 feet of snow that fell last week. Unfortunately, this lines up with where the best skiing and riding conditions are found. If you are riding in avalanche terrain and want to significantly decrease the chances of finding trouble today, slopes that already slid or shattered like a pane of glass have a much lower chance of producing either wet or dry avalanches. 

Regioni coperte