Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

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

Kernpunkte

Dangerous avalanche conditions persist due to the potential for large and destructive avalanches. The last round of natural avalanches that crushed valley bottom was observed on Wednesday. The potential for wet loose avalanches will increase as the sun warms the snow surface on the southern half of the compass. Simpler, smaller, and lower-angle terrain with a deep, uniform snowpack is safer than steep, complex terrain with variable snow depths and consequential hazards.   

Lawinenprobleme

  • Persistent Slabs

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

    Weak facets and collapsible crusts are widespread on the northern half of the compass and on some sunnier aspects at high elevations.  Recently formed slabs on top of these weak layers average 2 to 3 feet thick in wind-sheltered terrain. Slabs are thicker and harder in wind drifted terrain and can step down through older slabs to the ground.    This problem is becoming more stubborn to triggers, often requiring a thin spot on the slope, such as near buried rocks, trees, or where slabs thin from wind effects. Avalanches can break widely across multiple terrain features and be remotely triggered from flat terrain near or below steep slopes without warning signs. The problem is less common on south and southwest aspects, and can be avoided on slope angles consistently less than about 30 degrees.  

    These destructive persistent slabs released on Wednesday 2/19. 

  • Loose Wet

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

    As temperatures rise and the sun warms the snow surface, the potential for wet loose avalanche activity will increase. Pinwheels and roller balls are an early warning sign that this avalanche problem is developing, and a loose wet avalanche may release on a steep slope. Consider avoiding travel on or under steep sunny slopes as you see this avalanche problem developing, or if you find a few inches of wet snow on the snowpack surface. 

Avalanche Discussion

Active wind loading finally decreased on Thursday and Friday, and with that, the recent pattern of large to very large natural avalanches also came to an end. The likelihood of triggering a persistent slab avalanche has decreased since the beginning of the week, though the potential dealy consequence remains if one of these avalanches is triggered. As the slabs above those persistent weak layers have gained strength, the weight of a human is not affecting that weak layer as often. So, trigger points and areas where the slabs are thin are where these avalanches are more likely to be triggered. This may take multiple tracks on a slope before someone finds that trigger point. The average slab depth is more commonly deeper in the NW Mountains, and thus, the likelihood of triggering is lower than in the SE Mountain forecast area, where the slabs are often a little thinner, and the likelihood of triggering is higher. That is a big-picture view, and of course, there is some cross-over. 

The most notable change to conditions for this weekend and into next week will be the warming trend that is starting today. Wet loose avalanches were added to the problem list today, and we can expect this avalanche problem to produce some avalanche activity today. It will be interesting to see how this avalanche activity plays out over the coming days. The snow that accumulated last week has been slowly warming and is fairly thick. This will initially help hold back the amount or size of wet loose avalanches. A few inches of fresh snow accumulated on Friday morning and will more easily transition into a wet avalanche problem, while that late February sun will also be working hard to make a mess of things. If the size and frequency of wet avalanches increase on easterly and westerly aspects in the coming days, we may also see those wet avalanches begin to trigger larger persistent slab avalanches. 

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