Bulletin d’avalanche

Turnagain Pass and Girdwood

Chugach National Forest Avalanche Center
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Danger d’avalanche

Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

Avalanche danger is on the rise as weather moves in today. Dangerous conditions will develop, with natural and human-triggered avalanches likely where strong easterly winds are loading slopes above 1000'. These wind slab avalanches will be around 1' deep and will be becoming larger and more sensitive through the day. Avalanche danger will spike tonight, and is expected to reach HIGH by sunrise tomorrow.

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SPECIAL ANNOUNCEMENTS:

Chugach National Forest Motorised Use:  Turnagain Pass and Snug Harbor are the only areas in the Chugach National Forest that received enough snow to open, all other areas remain closed. Low snow cover hazards exist at low elevations, such as open creeks and alders. We have limited information for these zones and recommend extra caution if riding on steeper slopes.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1.5–2.5

    We've got another storm knocking on our door, and we're already seeing the winds ramp up ahead of the snow we're expecting tonight. Avalanche danger will be increasing through the day. It is likely a person will be able to trigger an avalanche a foot deep or deeper where the winds are building reactive slabs of snow. Natural avalanches will become more likely as the storm unfolds. The size and likelihood of these avalanches is increasing as of this morning, and that trend is expected to continue through the day. We will likely hit HIGH avalanche danger as precipitation intensity peaks late tonight.

    Be aware of changing conditions and increasing danger today. The wind has been at work building slabs over the past two days, and the increasing likelihood of natural avalanches means we have to be paying attention to steep overhead terrain as well as the slopes we are traveling on. If you are trying to beat the storm it will be important to keep your head on a swivel. Pay attention to increasingly touchy conditions and look for more stable snow in areas protected from the wind.

    Cornices: We almost always see large cornices forming and failing during wind events like this. These cornices are enough hazard on their own, but they also have the potential to trigger a much larger avalanche on the deeper weak layers we are tracking (see problem 2 for more on that). This is one more reason to avoid lingering under steep slopes. It is also important to remember that cornices have a habit of breaking much further back than we expect, so give them plenty of space if you are traveling along ridgelines.

      

    (1/18/2025)

    Predicted snow totals from 3 a.m. Saturday to 3 a.m. Sunday. Graphic courtesy of NWS Anchorage.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    2.5–3.5

    The weak layer of faceted snow that was buried nearly two weeks ago is still on our radar. The likelihood of seeing an avalanche fail on this layer is low, but it has the potential to make a very large avalanche. The layer is buried 6' deep on average, but the area where a person will be most likely to trigger an avalanche will be in upper elevation terrain with an unusually thin snowpack. This may be where winds have scoured snow away, or near rocks or cliffs. For slopes with a thinner overlying slab, the weight of a person applies more stress to that weak layer. We found this setup on the front side of Seattle Ridge on Thursday, and although that exact setup may not be widespread, we expect it exists in similar terrain across Turnagain Pass. 

    Areas with a thinner snowpack may have patterns related to slope characteristics (shoulders or ridgelines that tend to get scoured), but the pattern may also be geographic (areas on the south end of the pass that have a generally thinner snowpack than the north end of the pass). Keep this in mind as you travel; it is a good reason to use a little extra caution today.

Régions couvertes