Lawinenlagebericht

Gunnison

Crested Butte Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Veraltet — dieser Lagebericht ist 6 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

More destructive natural avalanches and rumbling collapses yesterday are a reminder that our snowpack is still unstable.  Conservative terrain: slope angles consistently less than 30 degrees are a great way to have a safe, low-stress day out there.   In or adjacent to steep terrain, don't expect clear warning signs before triggering a large and dangerous avalanche. The steady string of large remote triggers locally, and fatalities in neighboring regions, is all the feedback we need.  The most dangerous terrain remains west, north, east, and high-elevation southeast aspects. Wind-sheltered southerly slopes offer a safer, more trustworthy snowpack.  

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–3

    Slabs over buried weak layers 2 to 4 feet thick vary from stubborn to reactive under the weight of humans, and some could fail naturally today from windloading or precipitation.  These slabs are stiffening and often do not show obvious warning signs before someone triggers a large and destructive avalanche. The north half of the compass has the most fragile weak layers buried in the middle and bottom of the snowpack and is most likely to produce remote-triggered, widely propagating, and destructive avalanches from steep or adjacent flat terrain (see several videos illustrating this).  Some higher-elevation southerly terrain also harbors problematic structures.  Manage today's persistent slab problem by avoiding travel on or below terrain steeper than 30 degrees on the aspects highlighted above.

    A pair of large persistent slabs below Scarp Ridge, which likely ran during increased winds yesterday.  

    Photo: Irwin Guides

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    New snow and gusty winds are forming shallow slabs that might be sensitive to triggers on heavily drifted slopes near or above treeline.  Slabs will typically be small, but could be problematic if they push you into a terrain trap, or worse, if they step down and trigger a much larger persistent slab. Likewise, warm temperatures and wind drifting can cause cornice failures, which can trigger larger, persistent slabs.   Avoid these issues on wind eroded or wind sheltered terrain.  

    Wind transport began yesterday and should continue today with additional snow and more transportable winds.  

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Where rain falls on previously dry snow, small wet loose avalanches could occur.  Monitor precipitation type, and pay attention to the snow surface for pinwheels, rollerballs, or gloppy wet snow to identify the problem.  There's a rare chance that a small wet loose avalanche could gain enough mass to trigger a larger slab avalanche. 

    Rollerballs and pinwheels are a sign that wet loose avalanches are imminent.  

Avalanche Discussion

My mother-in-law has been visiting all week. She’s not a backcountry skier or snow scientist, but she’s been curious about all the avalanche hype in the media and in our backyard. Yesterday I told her we saw five more large to very large avalanches that likely ran in the past 24 hours, and she replied, “With just a little wind? Wow, it must really be fragile out there!”   She’s right. You don’t need to be an avalanche expert to recognize that our snowpack is problematic. Rumbling collapses, remote triggers, and sporadic natural avalanches after the storm tell the story. With more snow/rain and wind transport in the forecast today, I won't be surprised to see at least a few more big dawgs — destructive natural avalanches — especially on leeward terrain.

Despite the snowbanks around town making it feel like winter is back to normal, our snowpack is anything but normal. It was historically shallow heading into our recent loading events. January winds scoured shady start zones even thinner and weaker. Since our drought layers were buried on February 11th, the snowpack has nearly doubled in water weight: At Schofield Pass, we went from 10.5" of SWE to 17" in just over a week. That’s a significant load applied to a fragile foundation.  What makes this setup especially tricky is that recent snow has settled into stiff, dense slabs. They’re often strong enough to mask obvious warning signs...until they’re not. Sometimes, all it takes is crossing a thin spot, punching a snowmobile track through the slab, stepping out of your skis, or a hard turn in the wrong place to collapse the weak layer and bring down the house of cards.  

If your patience for conservative terrain is wearing thin, now is the time to reset expectations. Ski the steeps at the resorts, find a bed surface or south-facing slope you trust, redefine what a good day looks like, shop for a ski vacation to Alaska, or play CBAC Persistent Slab Bingo at home.  Our snowpack will improve over time, but it won't happen overnight.    

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