Bollettino valanghe

Summit Lake

Chugach National Forest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Yesterday's storm has passed, but conditions may still be reactive today. There is still a good chance that a person could trigger a very large avalanche failing on weak snow buried 2 to 4' deep within the snowpack. The fresh wind slabs that formed during the storm are around a foot deep and will likely remain reactive today. These problems will take careful snowpack evaluation, and it may be difficult to identify which terrain is holding the weakest snow. If in doubt, you can avoid the problem entirely by sticking to lower-angle terrain.

Problemi valanghivi

  • Deep Persistent Slabs

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

    The snowpack in the Summit Lake area has multiple layers of crusts and weak, faceted snow buried in the bottom half of the snowpack. This is 2 to 4' deep on average, and has the potential to make some very big avalanches. These deep persistent weak layers are a real challenge to assess, so for now the best way to manage them is by avoiding steep terrain in mid and upper elevations.

    These deeper weak layers have been giving us inconsistent feedback in stability tests, but they did produce a very widespread avalanche cycle a week ago. For now, we are still assuming there is a good chance a person will be able to trigger a very large avalanche in the Summit Lake area. Weather stations in the area recorded around 6" snow yesterday, which came in with strong winds. Although it's not a huge storm, this has added some weight on top of these weak layers, making them just a little more sensitive today.

    (1/18/2025) While Manitoba's west aspect is fairly deep, ridges facing more east are scoured above treeline, as pictured here. Photo: Andy Moderow

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–2

    The wind slabs that formed yesterday are probably around a foot deep and will likely remain reactive today. These are most likely to be found in steep terrain just below ridgelines, convex rolls, or in cross-loaded gullies. These will be the kind of terrain features to avoid today. A relatively small avalanche failing within that new and windblown snow also has the potential to trigger a larger avalanche failing on weak snow as mentioned in Problem 1 above. Considering this setup and the high likelihood of triggering an avalanche, it will be important to travel cautiously today, and avoid traveling in steep wind loaded terrain.

    Cornices: Yesterday's windy storm built large and sensitive cornices. Limit exposure to this overhead hazard, and be sure to give them plenty of space if you are traveling along ridgetops.

    Storm totals below begin Saturday evening when the snow started falling. The rain line stayed below around 1000' for Girdwood and Turnagain Pass this time around, and made it up to around 1500' for Summit Lake and Seward.

    • Girdwood: 18" snow/ 1.8" snow water equivalent  (SWE)
    • Turnagain Pass: 19" snow/ 1.3" SWE
    • Summit Lake: 8" snow/ 0.7" SWE
    • Seward/Lost Lake:  12" snow/ 1.0" SWE

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