Bollettino valanghe

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You may be able to trigger avalanches large enough to bury a person at upper elevations and on some middle-elevation slopes facing W-N-E. You may or may not observe obvious warning signs like snowpack cracking or collapsing before triggering a slide.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    What and where is it?  Slopes where 1.5-2.5 foot thick slabs lie above persistent weak layers—strong over weak layering—are suspect. You'll find this setup on many upper elevation slopes and on shadier slopes (W-NW-N-NE-E aspects) at the higher end of middle elevations. 

    How can you recognize it? On shadier aspects, you can easily feel the old crusts and sugary facets with your hands, ski pole, or snowmobile track. On sunnier aspects, the weak layers present as a series of crusts and facets and are not as obvious. Watch the great video below/to the right and read the Forecast Discussion for some tips on how to evaluate the slab.  

    How can you manage it?  Sadly, the only surefire option is to avoid avalanche terrain where denser slabs rest above the weak facets and crusts. Short of that, you can reduce your risk by avoiding large avalanche paths and those with ugly consequences if you are caught in a slide.

    Remember that Persistent Slab avalanches can break wider and higher on slopes (above you) than you might expect. Tracks on a slope do not guarantee the slope is safe—several skiers or riders may descend a slope only to have the next person trigger an avalanche. 

Avalanche Discussion

Recent observations show a trend of decreasing obvious signs of instability. In the past week, local avalanche professionals and experienced recreationists have been cautiously skiing or riding in avalanche terrain. What does "cautiously" mean? 

  • They are avoiding slopes with dense slabs.
  • They are avoiding most large + consequential (trees, rocks, cliffs, terrain traps, etc) avalanche paths.
  • They are avoiding "prime time" slope angles, slopes near 40*.

The weak layers near the bottom of the snowpack are most widespread near the upper/middle elevation boundary and at upper elevations. The distribution of the denser slabs is variable and difficult to describe; it's one of those "you'll know it when you feel it" scenarios. Some simple tips on evaluating the snowpack:

  • Slab avalanches are unlikely where your skis are hitting the ground with every step as you move uphill, or your sled track is constantly on the ground without grabbing much throttle. There is no slab. 
  • If your skis and poles are staying off the ground while skinning uphill, or you don't easily hit the ground when you step off your running boards, you should be thinking about the possibility of triggering slab avalanches.
  • If it takes effort to push your ski pole to the ground, or your sled track is not punching through to the ground when you grab some throttle, you're in the "money zone" where you may be able to trigger avalanches. 

Regioni coperte