Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

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

Kernpunkte

New and drifting snow will increase the avalanche danger through the day, creating dangerous conditions at higher elevations.   The most problematic terrain is on wind-loaded slopes that face northwest to east, where persistent slabs up to several feet thick are sensitive to human triggers and the increasing threat of naturals.  You can find fewer hazards riding in wind-protected terrain at lower elevations:  monitor for shallow instabilities entraining old weak snow as they run down slope.  

Lawinenprobleme

  • Persistent Slabs

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

    Each of our past two storms has caused a clear pattern of persistent slab avalanches on the north half of the compass near and above treeline.  At upper elevations, accumulating and drifting snow is increasing the threat of triggered slabs breaking on old weak layers.  The problem is less developed below treeline, where the snowpack is generally weak and cohesionless.  Persistent slabs are typically 1 to 3 feet thick and have the potential to break wider than you might expect, or can be triggered from flat slopes below steep terrain.   Shooting cracks or collapses are a clear sign of danger.  Choose conservative terrain with slope angles less than 30 degrees where you find a cohesive slab over weak faceted snow.  

    One of many large persistent slabs that failed naturally during last weekend's storm.  Similar, albeit larger, activity is expected this weekend.

  • Wind Slabs

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

    Westerly winds are drifting the new snow into thicker and more cohesive slabs on leeward features near and above treeline.  Wind slabs are forming on a mix of crusts, near-surface facets, and low-density snow that fell at the start of the storm.  Drifts will be forming below ridgelines and in cross-loaded gullies, evidenced by blowing snow and thicker deposits.  Steer away from windloaded slopes to avoid the problem.   On the north half of the compass, wind slabs could step down to trigger larger persistent slab avalanches.    

    An example of a wind slab from the archives.

Avalanche Discussion

The avalanche danger is rising more dramatically in the Northwest Mountains today, where storm totals are approaching two feet in the Slate and Kebler areas.   Heavy snowfall and increasing winds tonight and tomorrow are expected to spur a large and very dangerous natural avalanche cycle in the deeper zone.  The Southeast Mountains are lagging behind on storm totals (~5 to 9" so far) so avalanche problems aren't as large or widespread today.  The danger will increase significantly in our shallower zone tonight and tomorrow as well, but doesn't appear to cross the threshold into High danger (Level 4).  

Our buried weak layers have proven to be surprising and quite active so far this season, so give yourself a wide margin for error during this major loading period.   Last weekend, a persistent slab avalanche in Marble broke widely and engulfed four skiers, burying three of them.  Thankfully everyone survived (read the full accident report here).  Avalanche conditions are even more complicated this weekend, and they are becoming significantly more dangerous as this storm evolves.  You have multiple problems to manage now, and instabilities span around the compass. And like last weekend, slopes with the deepest coverage for early season turns are also the most problematic for avalanches.  Fear not, you can still enjoy the powder! Choose smaller terrain features and lower slope angles free of overhead hazards.  Avalanche hazards are smaller and more manageable in wind-sheltered terrain in the Southeast Mountains, though coverage is still quite thin for riding there. 

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