Bollettino valanghe

Seward and Lost Lake

Chugach National Forest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

Avalanche conditions are exceptionally dangerous right now. There were several near misses in Turnagain Pass yesterday, with skiers and riders triggering large avalanches remotely from low-angle terrain onto adjacent steeper slopes. Human-triggered avalanches 1 to 3' deep remain likely today. We recommend avoiding avalanche terrain by sticking to low-angle slopes, trying not to travel over terrain traps like creek beds or dense stands of trees, and steering clear of runout zones of overhead avalanche paths.

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SPECIAL ANNOUNCEMENTS:

We have issued a Special Avalanche Bulletin through the National Weather Service, in effect from 6 am today through 6 am tomorrow.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    In the Seward area, outflow winds have picked up in the past 24 hours with averages of 20 mph and gusts up to 45 mph. These winds can quickly transport the new snow from this weekend into fresh wind slabs on leeward aspects. The strongest winds appear to be near the town of Seward and at lower elevations, but we expect these conditions could impact areas throughout the Seward and Lost Lake forecast zone. You can keep an eye out for snow transport along ridgelines, shooting cracks, or hollow feeling pillows of recently wind-transported snow to help identify where wind slabs are located. Triggering a smaller wind slab avalanche could step down onto deeper weak layers and cause a much larger and more destructive avalanche. 

  • Persistent Slabs

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

    Recent avalanches: Several large to very large human-triggered avalanches occurred yesterday in popular locations in Turnagain Pass. Including Tincan Common, Eddie's Headwall, Main Bowl, and near the weather station on Seattle Ridge. Most, if not all, of these avalanches were remotely triggered from adjacent lower-angle terrain. In Summit Lake, there have been reports of widespread large collapses, and one observation of a natural avalanche on Tenderfoot from Saturday that was about 100 to 150' wide. No recent avalanche observations have come in from Seward and Lost Lake yet, but we expect conditions to be very similar to the neighboring forecast zones.

    Despite the calm weather today, avalanche conditions remain very dangerous. Human-triggered avalanches about 1 to 3' deep on buried weak layers are likely. Triggering an avalanche remotely from a low-angle slope adjacent to steeper terrain is likely with this type of snowpack setup. We strongly recommend avoiding avalanche terrain and staying out from underneath avalanche paths where the runout from overhead avalanches could bury a person. 

    This setup was caused by the prolonged cold and clear weather in December, which formed weak layers of faceted snow. These layers have been buried and stressed by the last two storms and are now about 1 to 3' deep. The most concerning locations for these weak layers are from about 1000 to 3000', where there is an ice crust in the snowpack that has helped make the weak layers more unstable. At higher elevations, we are also seeing a weak snowpack setup, but we have limited information about recent avalanche activity due to low visibility and a lack of observations. 

    In addition to the widespread large human-triggered avalanches, almost every observation we have received in the past week has reported large collapses or whumphing in the snowpack. These are clear signs from the snowpack that avalanche conditions are unstable.

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