Bollettino valanghe

Turnagain Pass and Girdwood

Chugach National Forest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

With over 2’ of snow falling since Saturday contributing to an unstable snowpack dangerous avalanche conditions exist today. There are several problems that have the potential to trigger large avalanches. Snow and wind slab avalanches 2 to 3’ deep are likely and may trigger a deeper avalanche on a buried weak layer. Wet snow avalanches will be likely and could run to valley bottoms. The safest option is a conservative approach into the mountains and avoiding spending time on or below steep slopes.

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Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2.5

    Over 2’ of snow has fallen since Saturday giving us another chance to enjoy soft snow and a little winter weather. That being said, avalanche conditions are dangerous and it will be easy to trigger a large avalanche 2’ deep in the storm snow. This is a lot of snow adding stress to a snowpack that is already unstable. Triggering a storm slab avalanche may step down to a weak layer that could trigger a large wet slab or persistent slab avalanche. The safest option is to stick to lower angle terrain away from steep overhead slopes and avalanche runouts.  

    Another 4 to 6” of heavy snow may fall today on top of lighter snow as the snow line is expected to increase to around 800’. This will mean that heavier snow will fall on top of lighter snow making it easier to trigger an avalanche in the new snow. Moderate winds yesterday have also moved snow into wind slabs that could be 3' deep or deeper. Recent avalanches, shooting cracks, collapsing snow and traveling on stiffer snow over softer snow are all clues that you may be on a slope that is ready to slide.  Due to the possibility of triggering a large avalanche in the new snow which may trigger a deeper avalanche the safest option is to ride lower angle terrain that is not below steep slopes or in avalanche runouts. 

    Storm totals below are from 12 AM Friday morning through 6 am this morning:

    • Portage: 10.5" Snow Water Equivalent (SWE), equaling 6 to 8' snow above treeline. 
    • Girdwood: 4.3" SWE equaling 2 to 3' snow. 
    • Turnagain Pass: 2.9" SWE equaling 12-24" snow.
    • Summit Lake: 0.6" SWE equaling 3-6" snow.
    • Seward/Lost Lake: 2.5" SWE equaling 16-24" snow.

    Cornice Fall: Stormy weather has pushed cornices to their breaking point. These may release naturally, possibly triggering a large avalanche above you. Avoid spending time under cornices and give them a lot of room if you are traveling on ridges.

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    Warm, rain soaked snow is now buried underneath 2’ of snow. This does not mean that wet avalanches are no longer a concern. In fact all of this new snow will add an immense amount of stress to the snowpack. Rain and warm temperatures have allowed liquid water to move into the snow where it tends to run like a creek along weak layers resulting in large wet avalanches which we have seen over the past week. 

    Wet avalanches including wet slab, wet loose and glide avalanches will continue to be a concern. These could be on any aspect and release naturally running to valley bottoms. If the sun comes out solar slopes may heat up increasing the likelihood of triggering wet loose avalanches. They may be larger and run further than expected.The snow conditions are complex right now. Trying to tiptoe around all of these problems to enjoy steep fresh powder will likely have severe consequences. The safest option is to avoid traveling on or below steep slopes. 

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    All of the rain and new snow the mountains have recieved will add a lot of stress to  the 2/14 surface hoar layer that is now buried at least 1 to 4' deep or deeper in some spots. This problem will be more concerning at mid elevations where liquid water is melting this layer and in upper elevations where snow has piled on top of it. This has been a extremely difficult layer to assess that has been responsible for many human triggered avalanches. It goes without saying, the safest option is to avoid traveling on or below steep slopes. 

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