Lawinenlagebericht

Northwest Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist last year abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

A potent winter storm has left dangerous avalanche conditions in its wake, especially near and above treeline. Avoid traveling in recently wind-loaded terrain, where you can easily trigger a large drifted slab and there's a chance it could step down to a more destructive deep slab.  Windward, south or southwest aspects offer safer travel options at higher elevations.  Below treeline, carefully evaluate the snowpack and terrain consequences for instabilities in this week's snow - soft slabs can break 1 to 2 feet deep on some slopes, most likely on very steep or northerly facing slopes.    

Lawinenprobleme

  • Wind Slabs

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

    Strong to extreme southwest finally eased up this morning, leaving sensitive slabs of drifted snow below leeward ridges and in crossloaded terrain.  Deeper, thicker-looking drifts and cracking are signs of fresh windloading. You can avoid wind slabs by traveling on wind-eroded or wind-protected slopes..  There is potential for a wind slab to step down and trigger a much larger avalanche that breaks on deeper weak layers.  

    A skier triggered wind slab on Purple Ridge  (3/4/2025) 

  • Deep Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3.5

    This loading event stressed deeply buried facets and depth hoar layers on the north half of the compass.  Slabs on top of these weak layers are several feet thick or more and capable of producing destructive avalanches.  The problem is stubborn to triggers: the most concerning terrain for triggering a deep slab is near and above treeline in rocky or wind-drifted terrain where slabs thin.  Avalanches can break widely across multiple terrain features and be remotely triggered from flat terrain near or below steep slopes without warning signs.   Avalanches in the upper snowpack could trigger the problem.   Deep slabs can generally be avoided on slope angles consistently less than 30 degrees or on southerly aspects.  

    There is also a spotty weak layer consisting of surface hoar or faceted crusts below this week's snow on the north half of the compass, which can give variable feedback or cause remote triggers involving recently formed soft slabs.   

    An example of a very large deep slab avalanche that broke on depth hoar layers near the ground in the Elk Mountains last week.  

  • Storm Slabs

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

    In wind-sheltered terrain, slab avalanches can break about 1 to 2 feet deep in the new and recent snow.  The warm-to-cold pattern of the storm is favorable for bonding on most slopes. Still, some may be reactive, especially on colder aspects where the storm snow accumulated on lower density or weaker snow earlier this week.  While most storm slabs will be small, larger or longer terrain features could produce slabs large enough to bury you.  Cracking on steep test slopes can help you identify the problem.  Monitor the bonding and amount of new snow and terrain consequences before traveling in steep terrain.  

    Cracking in the storm snow is a sign of unstable storm slabs. 

Avalanche Discussion

Head to our weather tab for a recap of our most recent storm, which brought about 8" to 16" to the forecast area accompanied by strong to extreme southwest winds.  Natural activity peaked overnight during the period of heavy snowfall and windloading, and should be rare today under quiet weather.  It will be interesting to see how our deeper weak layers responded to this storm. This storm was about half the water weight of the Cupid Crusher but brought the strongest wind speeds of recent months, with loading pointed directly at our most worrisome slopes for deeper instabilities.   It's an easy decision to give windloaded slopes at higher elevations a wide buffer today to allow the snowpack to catch its breath.

Below treeline is a bit trickier.  The snow came in warm and finished cold - favorable for storm slab bonding on most slopes.   However, there are some surprises lurking out there.  Those surprises will most likely be about a foot deep across most of our forecast area, and up to two feet deep near Kebler Pass and Upper Slate, which has seen more snow this week.  There are spotty layers of surface hoar or thin, collapsible crusts buried by this week's snow on colder aspects.  Choose terrain where the consequences won't be as serious if you trigger one of these somewhat random instabilities.  In shallower parts of our forecast area, the snowpack has a thinner and weaker snowpack structure that could also step down to older weak layers; again, on colder aspects.  Wind sheltered slopes on the southern half of the compass offer the fewest and easiest issues to manage, as described in this video.    

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