Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
3 · Erheblich
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Kernpunkte

The largest storm of the winter has left dangerous avalanche conditions in its wake, and the potential for a serious or deadly accident is very real today. New slabs are now deep enough that they may feel deceptively strong in some areas before unexpectedly releasing a destructive avalanche. Large to very large avalanches can also be remotely triggered from low-angle slopes connected to steeper slopes above. Natural avalanches remain possible on slopes receiving additional wind loading, and these avalanches could run far into lower-angle terrain and lower elevations. Southerly-facing slopes at lower elevations offer reduced avalanche risk. You can also use the avalanche terrain map to plan lower-angle routes that avoid avalanche start zones and runouts.

Lawinenprobleme

  • Persistent Slabs

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

    Persistent slab avalanches will break an average of 1.5 to 2.5 feet deep on buried persistent weak layers, and may run naturally today during periods of active wind-loading. The north half of the compass has the most fragile weak layers buried in the upper and lower snowpack (see video 1 & 2) and is most likely to produce natural releases, remote triggers from flat terrain, widely propagating, and destructive avalanches.  Southerly aspects have a more springlike snowpack structure, reducing the likelihood that avalanches break deeper and larger than the storm snow.  Manage today's persistent slab problem by avoiding travel on or below terrain steeper than 30 degrees on problematic aspects, including runout zones.

    A waist-high slab that was remotely triggered in Evan's Basin on Wednesday. The size of these avalanches will grow even further with higher elevations and/or more wind-loading. 

  • Wind Slabs

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

    Yesterday's widespread storm slab avalanche problem is becoming more specific to wind-affected and wind-loaded terrain. Yesterday's strong to extreme southwest winds have backed to the west and will be just strong enough to transport snow at times today. The simple travel advice is to avoid wind-loaded slopes on the lee sides of ridgelines and cross-loaded terrain features.

    A thick cornice that was remotly triggered on Wedneday in Evan's Basin. 

Avalanche Discussion

SWE totals since Tuesday are about 3.8" at Lake Irwin, 3.1" at Schofield,  1.5" at Upper Taylor, 1.1" at Butte. These remote weather stations were affected by the strong to extreme winds on Tuesday, and may not be totally accurate in recording what fell from the sky, but they still help give a ballpark. Two weather stations reported total snowpack height changes of around 25" at 11,000ft on Purple Ridge and 23" at 11,000ft on Mt Emmons. 

New slabs that are over 2 feet thick will help insulate the buried persistent weak layers from the weight of a human. That would mean that obvious signs of instability may become less frequent as we move past the intense loading period that occurred yesterday. If these conditions occur in the area that you are traveling, don't let yourself be fooled. The snowpack is at a record low; many areas have a very weak snowpack, and it shouldn't be trusted, especially right after the biggest storm of the winter. If you want more information on the old snowpack, last week's weekly summary would be a good place to start. 

The avalanche danger peaked on Wednesday during the intense loading period. The avalanche danger will try to ease today with the pause in accumulating snow. Avalanche forecasters remain uneasy or uncertain about the avalanche danger trend with the potential of additional wind-loading on some slopes today. The snowpack needs a moment to begin adjusting to yesterday's rapid loading, and if we continue to see wind loading today, the natural avalanche cycle will continue. An Avalanche Warning remains in effect. Another storm arrives on Friday and will continue to add stress to the snowpack. We are evaluating danger on a day-by-day basis at this point; stay tuned.

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