Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
Auf der Karte ansehen

Lawinengefahr

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

Kernpunkte

Our hearts are saddened with the loss of a beloved member of our community to an avalanche yesterday in the Anthracites.  The second serious accident in just the past three days highlights how dangerous and challenging our snowpack is right now.  Our buried weak layers are incredibly fragile and are at their tipping point beneath slabs up to several feet thick.   Increasing winds today will continue to spur natural avalanches.   Don't let the blue sky and fresh powder lure you into or below the type of terrain that has produced over 200 persistent slab avalanches this week:  Steep slopes that face west through north through east.  

Lawinenprobleme

  • Persistent Slabs

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

    To avoid getting caught in a dangerous persistent slab avalanche, choose low slope angles or seek out sunnier aspects.    Since last weekend, there has been a constant stream natural and human-triggered slab avalanches breaking on faceted weak layers near the ground.  The problem is both serious and tricky: recent incidents include helicopter evacuation and a fatality.   Be wary of traveling below steep, connected slopes: many of these avalanches were triggered remotely from low angle terrain and we continue to observe natural releases from wind loading.  The problem has been most active on slopes steeper than 35 degrees that face west through north through east at all elevations, and in a few cases, high southeast aspects.  If you are traveling on a slope that fits that description, expect to trigger it easily if it hasn't already avalanched earlier this week.  Slabs will be denser and thicker as you gain elevation towards wind loaded terrain features.  

    12/18: This remotely triggered persistent slab near Kebler Pass was over 2 feet thick.

  • Wind Slabs

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

    If northwest wind speeds increase as forecasted, yesterday's low-density snow will easily drift into reactive slabs on leeward and cross-loaded terrain features.  While most of these slabs will be small, they can push you into unsavory terrain or step down and trigger a larger, persistent slab avalanche.  Blowing snow will be pointing to where the problem is forming.  If you see wind transporting the snow, steer away from leeward terrain features below ridgelines, in gullies, or behind convexities to avoid the problem.  

    Example of a small wind slab on Mt. Emmons.

Avalanche Discussion

Yesterday's storm delivered up to a foot of snow (.6" SWE) to the Northwest Mountains and 3" to 8" (.2 to .4" SWE) for the Southeast Mountains.  Irwin Cat Ski Tenure reported their snowpack finally reached a tipping point, with numerous remotely and skier triggered slides from D1 to D2 on their west-facing terrain.  Other observers reported numerous natural avalanches and triggered slides throughout the forecast area, from Washington Gulch to Schuylkill Ridge to Whetstone.  With northwest winds increasing through the day, I expect we'll see continued naturals on higher elevation, leeward terrain.   Almost all of the avalanches in the past week (200+ and counting in our forecast area) have failed on the well-advertised weak layer that marked the end of our November and early December drought.   This exceptionally weak layer is now buried 1 to 3 feet deep: you'll find the thickest slabs in the Northwest Mountains, which have seen favored snowfall, and at higher elevations, which have seen favored wind loading.  Though the Southeast Mountains have picked up less snow in the past week, they clearly have a dangerous and unstable snowpack (Example A just beyond our forecast area, Example B from Brush Creek).  The danger is only slightly lower below treeline in this zone because slabs are generally thinner and less widespread, the exceptions being the bordering terrain like Snodgrass or Mt. Emmons.  Across our forecast area,  many slopes have flushed naturally over the past week, and many still hang in the balance.  Distinguishing between the two is getting harder with each subsequent storm and wind event.  Don't be fooled: You might find good stability on one slope that has previously avalanched and get caught in a widely breaking slab on the next slope.     

My heart goes out to everyone in town suffering from the loss of an icon and friend to all in the backcountry. The mountains around Crested Butte will feel empty without him.  We all know he found his peace and joy in the backcountry by traveling solo, which also comes with a higher risk.  If there's something else that we can learn from this tragedy, it's that the man who has made more turns in the CB backcountry than anyone else in this valley, or perhaps more turns than the entire valley combined, was caught by surprise by this year's fickle snowpack.   Our buried weak layers are exceptionally challenging right now.  Scroll through the pages of observations this week if you need any more evidence.  This is a great weekend to enjoy the powder, but make conservative terrain plans and stick to them so you don't get surprised.  

 

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