Avalanche forecast

Summit Lake

Chugach National Forest Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Summit Lake got mostly wind and just a trace of snow out of yesterday's storm. The biggest concern today is the chance of a human triggering a large avalanche 2 to 4' deep above 1,000'. Fresh wind slabs up to 1' deep could be more likely for a human to trigger in the upper elevations, but they are located in the same place as the more dangerous deep persistent slab problem. These large avalanches are more likely to be triggered from a thin spot in the snowpack and can be completely avoided by sticking to lower angle slopes.

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SPECIAL ANNOUNCEMENTS:

Department of Transportation Avalanche Closure Notification for Wednesday January 22nd, 2025:

There will be intermittent traffic delays Wednesday January 22nd, 2025 on the Seward Highway for Avalanche Hazard Reduction work. From milepost 95-100 on the Seward Highway, North of Girdwood and South of Anchorage, at Bird Flats. Motorist should expect delays of up to 45 minutes between 09:00 AM and 12:00 PM. Updates will be posted on the 511 system. http://511.alaska.gov

Avalanche problems

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2.5–3.5

    Two days ago one of our forecasters was traveling on the ridge of Tenderfoot and felt a collapse (whumpf). He and his partner dug a pit near that location and got unstable results on a layer of weak snow near the ground. This is not surprising because we know the structure of the snowpack in Summit is poor, there is a large slab of snow sitting on a weak layer. There was also a large avalanche cycle just over a week ago. This avalanche cycle combined with unstable test results is telling us there are still chances a person could trigger one of these large avalanches in the Summit Lake area. This problem is difficult to assess, so if you are riding steep slopes it will be important to avoid thin places in the snowpack, which are likely trigger spots, and travel one at a time watching your partners.

  • Wind Slabs

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

    The winds didn't verify in Summit Pass like they did in Turnagain Pass yesterday, but the winds were still strong enough to create some fresh wind slabs above 2,500'. These wind slabs may be small, but the bigger concern is that they are located in the same place as the deep persistent slab problem. Triggering a wind slab avalanche could trigger a larger avalanche (described above), which would be a much more difficult incident to survive. Wind slabs are usually located below ridgelines and in cross-loaded gullies and can be identified by feeling for firm snow over soft snow. A shooting crack is a sign the snowpack needs more time to stabilize.

    Cornice: As each storm passes cornices continue to grow. Corices are prime for failure during and right after a storm so steering clear both above and below cornices today is a good plan.

    Dry Loose Avalanches: Natural dry loose avalanches were observed in Turnagain and Summit Lake two days ago. This type of avalanche is not generally as dangerous as a slab avalanche, but could catch us by surprise and carry us into trees or over a cliff if enough snow becomes entrained.

    Storm totals from yesterday above 1,000':

    • Girdwood: 1.3" water (~12" snow).
    • Turnagain Pass: 1.3" water (~12" snow).
    • Summit Lake: 0.1" water (~trace -1" snow). 
    • Seward/Lost Lake: 0.6" water (~6" snow). (Another 0.7" water is expected today or 7-8" snow.)

    (1/20/2025)

    Cracks shooting out from you is a sign of a wind slab and unstable snow. This one occurred on Monday at Sunburst.

    Photo submitted anonymously

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