Lawinenlagebericht

Northwest Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
4 · Gross
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

The avalanche danger is CONSIDERABLE (3 of 5) on Wednesday morning with the expectation that it will rise to HIGH (4 of 5) by this afternoon or early evening. Dangerous avalanche conditions exist now and human-triggered avalanches are likely. The threat of natural avalanches increases through the day, and by this afternoon travel in or below avalanche terrain is not recommended. These natural avalanches can push into low-angle terrain or even impact some backcountry roads. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    1.5–3

    Many slopes have a very weak foundation, and new slabs forming over these persistent weak layers will be reactive to the weight of a human, or they may release naturally without any warning. A triggered avalanche could also step down to deeper weak layers near the ground, becoming much larger than expected, and producing a destructive avalanche. This avalanche problem can propagate widely through the terrain, or be remotely triggered from low-angle slopes connected to steeper slopes. This is not the day to try and outsmart this avalanche problem. 

    Avalanches could step down into deeper weak layers such as this human-triggered avalanche on 12/27.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    Warm temperatures combined with new snow are creating widespread thick slabs. Avalanches averaging 8 to 18 inches thick will be likely to human trigger on many slopes near or above 35 degrees in steepness. Careful snowpack evaluation and cautious route finding will be essential when traveling near avalanche terrain. Areas, where this avalanche problem overlaps the persistent slab avalanche problem, should be avoided. 

    Shooting cracks or a collapsing snowpack are obvious red flags that the snowpack is unstable. 

Avalanche Discussion

Complicated avalanche conditions have developed and another natural avalanche cycle will likely occur in the near future. The persistent slab avalanche problem is the most complex and will produce very dangerous avalanches. The complexity comes from how this avalanche problem will become reactive in different areas at different times. For example, on slopes that previously avalanched this winter, the old snowpack is exceptionally weak. Those areas will become the most reactive first, with natural avalanche activity already beginning. Other slopes will be able to hold more load, such as sun-crusted southerly facing slopes, or the previously wind-hammered alpine terrain. These slopes will also reach their breaking point eventually, but at a different time, which will be more difficult to predict. Their ability to hold more load will also result in larger more destructive avalanches when they release. The observations tab has several good reports documenting these weak layers and the snowpack structure heading into this storm. 

Managing the avalanche problems will be complex and difficult this morning. Dangerous avalanche conditions have already developed. If the weather forecast varifies, then natural avalanches will become larger in size and more widespread. By this afternoon traveling in or below avalanche terrain will not be recommended as natural avalanches will run into low-angle terrain and may even impact some backcountry roads.

Overnight snow totels as of 5am are estimated below. 

Schofield Pass: .7 SWE

Gothic: 7" snow and .74 SWE

Upper Slate: 6" snow

CBMR: 6.5" snow

Brush Creek: at 11,400ft 6" snow

Upper Taylor:  .2 SWE

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