Lawinenlagebericht

Northwest Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

Low-angle terrain  - slopes consistently less than 30 degrees - is the safest way to enjoy the feet of recent snow that overwhelmed our weak snowpack.  Unstable slabs are often thick enough that they don't provide consistent warning signs before releasing a deadly avalanche.  Look no further than the recent naturals and large remote triggers locally, and the several close calls and fatalities in neighboring regions for feedback.  This video from Carbon Peak yesterday will amaze you with what our snowpack is capable of.   The snowpack is most dangerous where the powder is still good: west, north, east, and high southeast aspects.  Wind-sheltered southerly aspects offer less hazardous conditions: manage for smaller wet-loose issues developing on these slopes once the snow surface gets wet.  

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–3.5

    Slabs over buried weak layers 2 to 4 feet thick (deeper on drifted terrain) are sensitive to human triggers. These slabs are stiffening and often do not show obvious warning signs before someone triggers a large and destructive avalanche. The north half of the compass has the most fragile weak layers buried in the middle and bottom of the snowpack and is most likely to produce remote-triggered, widely propagating, and destructive avalanches from steep or adjacent flat terrain (see several videos illustrating this).  Recent natural avalanche activity suggests that higher-elevation southerly terrain also harbors problematic structures.  Manage today's persistent slab problem by avoiding travel on or below terrain steeper than 30 degrees on problematic terrain highlighted above.

    A very large remotely triggered avalanche on Carbon Peak yesterday.  

     

  • Loose Wet

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

    Rising temperatures and strong solar radiation will wet the snow surface on the southern half of the compass, causing shallow point releases from very steep or rocky slopes.  Most of these sluffs will be small, though in longer, steeper terrain, they might grow larger.  In some rare cases, a loose avalanche could release a larger slab as it descends.  Monitor the snow surface for rollerballs, pinwheels, gloppy snow, or sluffing on steep terrain.  Move away from consequential and larger terrain and consider overhead hazards if this problem develops.  

    An example of a Wet Loose avalanche from last weekend on an alpine south slope. 

Avalanche Discussion

With snow surfaces getting wet on southerlies today, Mother Nature will be luring powder seekers towards the colder side of the compass, where we have seen the vast majority of persistent slab avalanches in the past week (along with high, southeast aspects).  Our forecasters are going cross-eyed documenting the hundreds of avalanches that ran during and just after last week's storm, which brought several feet of snow and strong winds to the mountains.  Note the patterns: the majority have been large enough to bury or kill you (D2), and some have been large enough to destroy a house or car (D3).  Yesterday's video from Carbon Peak is an eye-opening example of what our current slab-and-weak-layer setup can do.  This persistent slab problem is the real deal and requires a more cautious approach to terrain than we've seen all winter, given its long remote potential and deadly size.   Opportunities to reduce your risk exist where slabs flushed during the cycle; otherwise, treat the terrain highlighted by our persistent slab rose as untrustworthy, even if the snowpack isn't producing signs of instability.  

While stability has been relatively good on most mid- to low-elevation southerlies in the past few days, this could change during the warmer parts of today as wet loose avalanches develop.  Unlike the persistent slab problem, wet loose avalanches are fairly easy to recognize and smaller.  One area of concern is whether a relatively small wet loose triggers a larger persistent slab where the problems overlap. Keep the potential for natural activity on your radar still - we saw quite a few large to very large natural avalanches release as recently as Saturday after the storm had passed.   

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