Lawinenlagebericht

Gunnison

Crested Butte Avalanche Center
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Lawinengefahr

Thu
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

Dramatic wind drifting has brought some wind-loaded slopes to their tipping point.   In the past two days, destructive avalanches have broken on weak layers near the ground (Axtell, Scarp Ridge) and weak layers in the upper snowpack (Schuylkill Ridge).  In sheltered terrain on shady aspects, avalanches breaking on buried weak layers in the snowpack are also a concern but less common.  The safest riding is on wind-protected terrain on the southern half of the compass.  

Lawinenprobleme

  • Persistent Slabs

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

    In the past two days, we've observed large slab avalanches breaking on weak layers in the upper snowpack and near the ground at upper elevations.  These issues are most concerning on colder, shadier aspects highlighted by the persistent slab rose, especially on wind-loaded terrain.  Smaller but similar avalanches are possible below treeline.  Expect variable and infrequent feedback.  Choose simpler, lower-angle terrain or southerly aspects to reduce your risk.  

    A pair of persistent slabs broke on deep weak layers on Mt. Axtell yesterday from wind loading.  

  • Wind Slabs

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

    Yesterday's intense wind drifting formed fresh slabs of drifted snow on leeward terrain features. Winds shifted from southwest to northwest and will continue at transportable speeds on some higher terrain today.   Expect to find thicker, denser drifts below ridges, underneath cornices, and cross-loaded into gullies.  Cracking in the new snow indicates you have found sensitive wind-blown snow. Avalanches in the freshly drifted snow could step down and release a much larger persistent slab where the problems overlap.  You can avoid the problem in windsheltered or wind eroded terrain. 

    A shallow Wind Slab from earlier this week below a leeward ridgeline.  

Avalanche Discussion

Wind drifting has been relentless since Monday, keeping high elevation and leeward terrain under distress.  During a period of better visibility yesterday morning, we spotted a handful of large avalanches that ran naturally at higher elevations on buried weak layers.  The peak of natural instability likely occurred during yesterday's wind event, and sensitivity to human triggers will decrease moving forward.   Some slopes will be stubborn today, while others may be reactive.  Avoiding steep, windloaded terrain is a good strategy today while the snowpack adjusts. Multiple weak layers are at play, making for challenging snowpack assessments.  The recent human-triggered avalanches on Schuylkill Ridge (Thanksgiving Bowl and Yogis) likely failed on near-surface facets that were buried by last week's storm.  This pre-burial observation describes the tricky variability of this layer, which is most likely to misbehave where it is larger-grained and stressed by wind-loading (E to NE aspects NTL seem to be a bullseye).  The destructive avalanches on Axtell broke on deep weak layers near the ground, similar to this very large avalanche off of Schuylkill Ridge over the weekend.   These avalanches share some characteristics:  steep, windloaded, shady aspects that have previously avalanched multiple times this season, thus holding a shallower and weaker snowpack.  

Though the same weak layers exist on shady aspects below treeline, the snowpack isn't as stressed, and recent slabs aren't as well-developed.  Triggering a persistent slab up to D2 in size is possible on northwest to northeast aspects.  You can find a more trustworthy snowpack on the sunnier side of the compass, where meltwater has strengthened the deep layers and cooked off most of the near-surface weak layers.  

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