Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Another round of snowfall and wind will stress weak layers in the snowpack.  You can trigger a dangerous avalanche on many steep slopes at all elevations.  Drifted terrain is the most dangerous as avalanches could break deep and wide, and grow large enough to be unsurvivable.  Maintain a high index of suspicion for all avalanche terrain during today's loading event.  Conservative low-angled terrain selection with careful management of steep slopes above your group remains the best defense.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1.5–3

    Persistent weak layers in the middle and bottom of the snowpack were overloaded by 3 to 6 feet of new snow in the past week and another storm on Friday will further stress these weak layers. Destructive avalanches have released around the compass and at all elevations over the past few days, and plenty of other slopes are hanging in the balance waiting for a human trigger.  Persistent slab avalanches can propagate widely through the terrain, or be remotely triggered from low-angle slopes connected to steeper slopes. Leeward start zones at higher elevations could release naturally today with additional wind loading, with the potential for very large natural avalanches (up to D3+).  At lower elevations, persistent slabs are sensitive to triggers on some slopes and are more commonly large (D2) in size.   You can avoid the problem by traveling on slope angles that are consistently less than 30 degrees without overhead hazards. Give yourself a wide margin for error given how consequential the problem is right now. 

    1/4:  A destructive natural avalanche in Red Lady Bowl broke full width on Wednesday.  This avalanche would be hard to survive.

  • Wind Slabs

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

    Previous westerly winds formed sensitive drifts on leeward slopes at higher elevations the past few days. Today another round of snow and westerly winds will continue to build slabs on leeward terrain.  These drifts could pose a hazard themselves or step down and trigger a much larger persistent slab.  Avoid travel on or below recently drifted slopes.  Though less likely, the new snow could also be reactive as a storm slab on steep, wind-sheltered terrain.

    1/3:  A pair of soft slabs involving the new snow, skier triggered on a drifted rollover.  

Avalanche Discussion

Let's consider the big picture; a prolonged stormy period from December 27th through January 4th produced several natural avalanche cycles on all aspects and at all elevations.  The avalanche activity was spread between both forecast zones.  Take a look through the media gallery below and the CBAC's observations page or look at the Avalanche Rose to get a clearer idea of the size and scope of avalanche activity.  Thursday, January 5th, offered a tiny period of quiet weather when weak layers could adjust to the burdensome slabs above, but that window quickly ended with another storm piling up snow on Friday.  There is a delicate balance between improving and deteriorating avalanche conditions.  Today's storm will start tipping the balance back towards an increased risk of natural avalanches on drifted slopes and an increase in sensitivity for human-triggered avalanches.

Drifted terrain remains the most dangerous as snowfall and wind-loading have been nearly constant for 10 days.  Avalanches on drifted terrain, natural or human-triggered, could grow to very large sizes and be unsurvivable.  This applies to both the Northwest and Southeast Forecast Zones.  Giving a wide marge to suspect drifted terrain will serve you well.  Until a prolonged period of stable weather arrives, drifted terrain remains scary and dangerous.

Sheltered slopes are a bit more nuanced.  For areas in the Northwest Mountains, where the snowpack is deeper and more uniform, there is less of a chance of triggering a deep-breaking avalanche.  Persistent Weak layers are more than a meter deep and trending towards stubborn for human triggers.  However, this observation from near Pittsburg tempers that attitude as a natural avalanche from a below treeline slope overran a commonly used snowmobile route just in the past few days.  Additionally, sheltered slopes that previously avalanched this season in the Northwest Mountains may have increased sensitivity for human triggers due to a shallower snowpack. For areas in the Southeast Mountains, where recently formed slabs are thinner and weak layers more pronounced, the threat of human-triggered avalanches on sheltered terrain remains elevated particularly as snowfall stacks up today.  This recent observation from Cement Creek and this report from Snodgrass help to illustrate the point.

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