Bollettino valanghe

Summit Lake

Chugach National Forest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

The weather is clearing but the avalanche conditions remain dangerous, especially at higher elevations. It will be easy to trigger an avalanche where winds have recently blown snow into steep terrain. The biggest concern is triggering a very large avalanche failing 4' deep or deeper on weak snow buried near the bottom of the snowpack. There is also still a good chance a person will be able to trigger an avalanche 1 to 2' deep where yesterday's winds created a new round of sensitive slabs at upper elevations. Look for safer conditions and better riding in terrain that has been protected from the wind, and consider avoiding steep alpine terrain entirely while the snowpack has more time to settle.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–2.5

    The strong easterly winds we've been seeing are expected to die down during the day, but the fresh wind slabs they have formed should still be reactive through the day. The most sensitive avalanches will likely be a foot or two deep, which will be plenty big enough to bury a person. They may also trigger a larger avalanche failing deeper in the snowpack (mentioned previously in Problem 1).  The most dangerous terrain will be steep, wind loaded slopes at elevations above 2500'. Luckily, on days like this the most stable snow will also be where the best surface conditions are. Look for this on slopes that have remained sheltered from the recent strong winds, and consider staying off the steep terrain in the alpine while the snowpack has a little more time to adjust.

    Take warning signs like shooting cracks or collapsing as a clear sign of unstable snow, but be aware that you may not always see these even when conditions are dangerous. The simple combination of stiff snow on top of softer snow may be the only sign you get today.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2.5–3.5

    It has been confirmed- the mountains around Summit Lake fell apart during the most recent storm. This is the second major avalanche cycle in the area this week, and based on the size and extent of the avalanche activity, we clearly have a problem with those multiple weak layers of snow buried within the snowpack. This setup will be most problematic at elevations above 2500', where the snowpack has remained cold and dry, and the weak faceted snow has gained the least strength. This also overlaps with the terrain where fresh wind slabs (mentioned in Problem 2 below) are most reactive. These weak layers will be difficult to assess, so the best way to manage it is to avoid steep upper elevation terrain for now.

    These clear periods shortly after a storm are a deceptively dangerous time to be out. Although the snowpack is not nearly as touchy today as it was during the peak of the storm, there is still a good chance that a person could trigger a large avalanche. This is supported by the conflicting feedback we got from snowpits yesterday- some tests were showing unstable snow while others were not- but the recent major loading event and resulting avalanche cycle are all we need to know that this snowpack is still problematic. In the long term this heavy load will be a great way for the snowpack to gain strength, but we need to give it some more time to adjust before we can be confident that a person won't trigger a very large avalanche.

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