Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

24-hour snow totals were about 9" on the CBMR Pow Camera, while moderate to strong westerly winds have consistently been blowing for a few days now. Dangerous avalanche conditions exist near wind-loaded terrain with the further possibility that natural avalanches could occur in these areas. In wind-sheltered areas, a layer of surface hoar buried 1 to 2 feet deep has created an untrustworthy snowpack. Careful snowpack evaluation or lower slope angles are recommended in those wind-sheltered areas. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1.5–2

    Since last Wednesday, 12,000ft weather stations have recorded westerly winds averaging into to 20mph range and gusting into the 30's to 50's mph range. Steady snowfall has continued to keep snow available for transport onto lee terrain features. This has created dangerous wind slabs and is further loading persistent weak layers buried deeper in the snowpack. Natural avalanche activity is possible during periods of heavy precipitation rates or active wind-loading. 

    An example of a large avalanche that failed on a wind-loaded terrain feature last week.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1.5–2.5

    A new round of weak layers was buried on February 2nd. These weak layers consist of widespread surface hoar and facets on most east, north, and west-facing slopes, and along with some faceted crusts on higher elevation southerly aspects. Slabs 1 to 2 feet thick over these weak layers can be triggered by skiers and riders. This avalanche problem can be remotely triggered from flat terrain, or may propagate further than expected.  Shooting cracks or collapses are a clear sign of danger, but these obvious signs of instability will not always show themselves before an avalanche releases.  There is isolated potential to trigger older, larger slabs on weak layers deeper in the snowpack, most likely from shallow terrain features or step-down avalanches.  

     

    This skier-triggered persistent slab avalanche likely failed on a layer of buried surface hoar last weekend.

Avalanche Discussion

There is some great snow to ride and dangerous avalanche conditions to manage. Your lowest risk for triggering an avalanche exists on lower elevation southerly facing slopes. If you want to ride some powder and simplify the avalanche conditions then this is the terrain for you. Stay on the lookout for the occasional wind-loaded slope in these areas and remember that you can also reduce any uncertainty with your choice in slope angles. 

The recent weather has painted a clear picture that wind-loaded terrain is dangerous. Confidence in the avalanche forecast decreases in wind-sheltered terrain highlighted by the persistent slab avalanche problem. We are unsure how much weight needs to be added to the snowpack to notably reactivate the weak layers buried in the upper snowpack. The primary weak layer here has been a layer of surface hoar that is buried 1 to 3 feet deep across the forecast area. Last weekend there were two notable accidents and many other avalanches that released on this weak layer. In the last few days avalanche activity on this layer has quieted down, and stability tests are producing a wide variety of results. What we do know, is that the snowpack structure is untrustworthy, with a notable persistent weak layer in the upper snowpack capable of producing large and dangerous avalanches. We may not be able to accurately predict how reactive avalanches will be on this weak layer today, but we can certainly look at the structure and say that it deserves careful snowpack evaluations and/or cautious route-finding to manage. The below treeline avalanche danger was increased to CONSIDERABLE to account for this recommended travel advice. 

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