Lawinenlagebericht

Northwest Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 7 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

The most suspicious terrain for triggering a large avalanche can be found on wind-drifted slopes.  Previous winds predominantly came from the north and northwest, commonly forming slabs on easterly and southerly features and crossloading on other aspects.  A trickle of observations report collapsing near and above treeline, so heed any warning signs.  You can reduce your risk by avoiding drifted terrain and favoring wind-protected slopes at lower elevations.

Lawinenprobleme

  • Persistent Slabs

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

    Most avalanche concerns today involve slabs of drifted snow that formed over the facets and faceted crusts from our January drought.  These slabs, up to several feet thick, could remain sensitive to human triggers on some leeward terrain features, most commonly on east to south-facing aspects at higher elevations and on crossloaded features elsewhere.  Because these recent slabs formed on highly variable snow surfaces, expect hit-or-miss feedback as you move through the terrain.  Collapses and shooting cracks are clear red flags. There is isolated potential for a slab failing in the upper snowpack to step down and trigger a deeper, harder avalanche near the ground. The most reliable way to manage this problem is conservative terrain selection—sticking to slopes under 30° or small terrain features without terrain traps.   Lower-elevation southerly aspects offer the safest snowpack, and slabs are typically less developed in wind-protected or wind-eroded terrain.

    Several large avalanches that failed on windloaded southeast-facing slopes over the weekend.  

Avalanche Discussion

The avalanche danger is on a gradual downtrend after last weekend's loading event and natural avalanche cycle.  However, forecasters continue to experience collapsing while traveling in near and above treeline terrain, often on easterly and southerly aspects (Galena, Wolverine Basin).  Weak snow is common beneath last weekend's storm, but prevailing winds from the northwest preferentially loaded easterly and southerly aspects.  The avalanche activity rose highlights this pattern of increased avalanche activity on wind-drifted easterly and southerly terrain.  You should expect to find drifted slabs on westerly and northerly aspects, but less frequently, and often due to crossloading.  The avalanche activity and signs of instability suggest a cautious approach to terrain with evidence of recent drifting.  This video shares more information about the concerning structure Zach encountered in Rock Creek while investigating a natural avalanche.

Without the additional stress from windloading, the low-density snow that fell over the weekend seems to have found a happy medium with the fragile facets below.  Wind-sheltered terrain appears to offer less risk.  If you choose steep terrain protected from the wind stay alert for exceptions and heed warning signs like cracking or collapsing.  Some terrain below treeline has become extremely weak and presents a loose avalanche problem where you encounter an entirely faceted snowpack.  This structure is most common on the north half of the compass.  Forecasters triggered a few facet sluffs on steep, northerly terrain while exiting Wolverine Basin yesterday.

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