Avalanche forecast

Summit Lake

Chugach National Forest Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

There are a variety of avalanche concerns in the Summit Lake area today. The biggest problem remains wet snow avalanches, which have been failing deep in the snowpack. It is also still possible to trigger a large avalanche failing on a weak layer of buried surface hoar that is about a foot deep, and may produce avalanches even at upper elevations where the snowpack is still dry. There is also a good chance a person will be able to trigger an avalanche up to a foot deep where recent winds have drifted snow into reactive slabs.

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SPECIAL ANNOUNCEMENTS:

We have published the final accident report for the March 22 avalanche fatality on Seattle Ridge at Turnagain Pass. It can be found here.

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Recent Avalanches: Glide avalanches, wet loose, and wet slab avalanches have been releasing in Turnagain Pass, Girdwood Valley, Summit Lake, and near Lost Lake for the past week. Some have been very large running to valley bottoms. 

    The next round of active weather is arriving this morning, but it is looking impacts in the Summit Lake zone will remain minimal. We are now seeing snow at sea level, but the snowpack has not been able to refreeze since early last week. Water has been impacting weak layers buried earlier this season - including the 2/14 buried surface hoar layer discussed in Problem 2 - which increases the chances of seeing big avalanches failing deeper in the snowpack.

    Wet avalanches remain the biggest concern for now. This includes wet loose, wet slab, and glide avalanches. These will be most likely at and below treeline, and they may run into lower elevation runout zones. Since the Summit Lake zone has seen less water over the past two days, the chances of seeing these wet avalanches are smaller than in the Turnagain Pass or Seward/Lost Lake zones. However, the consequences of these avalanches is severe. Approach steep terrain with caution today. If you notice you are sinking in up past your boots in wet and unsupportable snow, it is time to head to low-angle slopes. The past two days of light rain on snow will make northerly aspects just as suspect as southerlies today, so the typical strategy of heading to shaded slopes will not be as effective.

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

    • Portage: 8.7" Snow Water Equivalent (SWE), equaling 4 to 6' snow above treeline.
    • Girdwood: 3.2" SWE equaling 1.5 to 2.5' snow.
    • Turnagain Pass: 1.9" SWE equaling 12-18" snow.
    • Summit Lake: 0.3" SWE equaling 1-3" snow.
    • Seward/Lost Lake: 1.9" SWE equaling 12-18" snow.

    Cornice Fall: These last few days of wet and windy weather will be pushing cornices to their breaking point. These may fail naturally, and they may trigger larger avalanches when they land on a slope. Avoid spending time below cornices, and give them plenty of room if you are traveling along ridgelines.

    (4/7/2025)

    Predicted precipitation totals from 4 am this morning through 4 am tomorrow.

    Photo: NWS Anchorage

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–2.5

    This weekend's weather has added a bit more stress to the layer of surface hoar that was buried on 2/14 and remains a concern today. As mentioned above, this layer has likely been impacted by liquid water at and below around 2500', but that is not the only concern. At upper elevations the weight of this new and windblown snow is pushing this layer closer to its breaking point. The layer is around a foot deep on average, and has the potential to make a very large avalanche.

    This will be difficult to assess. We had been seeing conflicting test results on this layer prior to this most recent storm, and in some cases we found stable test results on slopes that produced avalanches later. Because of the high uncertainty and the severe consequences of triggering an avalanche,  steep terrain needs to be approached cautiously. Avoid traveling on slopes with large start zones or terrain traps like gullies, cliffs, or trees in the path or runout zone. You can avoid this problem entirely by avoiding traveling on or below steep terrain.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    The wind has been the biggest factor weather-wise in the Summit Lake zone for this storm. It remains possible to trigger an avalanche up to a foot deep where winds have drifted snow into reactive slabs. This will be most likely in steep terrain just below ridgelines, convex rolls, or steep gullies. Watch out for shooting cracks or collapsing as key indicators of unstable snow. This problem should not exist in terrain that has been sheltered from the winds over the weekend. With winds calming down today, we expect this problem should be quick to heal.

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