Lawinenlagebericht

Turnagain Pass and Girdwood

Chugach National Forest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Sun
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist last year abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

A weak layer of buried surface hoar 1 to 3' deep continues to be our main concern. Very large human triggered avalanches are still possible with the snowpack providing no signs of instability before triggering an avalanche. In the past two weeks, there have been several accidents and near misses due to avalanches on this layer. We recommend continued conservative decision-making by sticking to low angle terrain and avoiding slopes connected to steeper terrain above.

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SPECIAL ANNOUNCEMENTS:

Come find us at the Seattle Ridge motorized parking lot on Saturday, March 22 for our annual Turnagain Pass Avalanche Awareness Day! We will be there with Alaska Mining and Diving Supply and the Alaska Avalanche School to chat about avalanches and current conditions and to hang out with the good people of the southcentral Alaska winter community. AMDS will have demo snowmachines, and we’ll be holding down the grill and the fire pit. Stop by anytime from noon until 4:00 p.m. Details Here.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    It has been almost a week since the last significant avalanche on the Valentine's Day buried surface hoar layer. This is a good sign, but it doesn't mean we are out of the woods yet. From what we have seen in the field, folks have been doing a great job sticking to mellow terrain. That means there haven't been many slope testers edging into steeper terrain, so we don't have a good sense of how sensitive the weak layer is to human triggering. Based on past experience, buried surface hoar tends to remain human triggerable for a long time and can give zero signs of instability before a large avalanche releases.

    Another tricky aspect of buried surface hoar instabilities is that our typical tools for assessing the snowpack are not reliable (snow pits, hand pits, test slopes, etc). You could dig a perfect pit and find nothing, then step onto the adjacent slope and trigger an avalanche due to the spatial variability of the weak layer. For that reason, it is important not to try and outsmart this type of problem. The only way to reliably avoid the potential for triggering a large avalanche is to continue being patient by sticking to low angle terrain and avoiding slopes that are connected to steeper terrain above. 

    In addition, there is a second layer of buried surface hoar about a foot deep, which has caused some smaller avalanches in Turnagain Pass this week. This layer is less concerning because the potential size of the avalanches is smaller, but it is still worth being aware of. Other concerns today include smaller avalanches releasing in the 6-12" of new snow from this week, loose snow avalanches on steep slopes triggered by the sun, and cornice fall. Any of these smaller avalanches could trigger a larger avalanche on the Valentine's Day buried surface hoar. 

    Glide avalanches are also still an issue and we have seen several recent glide avalanches release near Girdwood this week. Try to avoid traveling underneath glide cracks or expose one person at a time to minimize time underneath these unpredictable hazards. 

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