Bollettino valanghe

Banner Summit

Sawtooth Avalanche Center
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Pericolo valanghe

Sat
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

The combination of recent snow and wind are creating dangerous avalanche conditions. You could trigger avalanches involving just the recent storm snow or very large avalanches that fail on weak layers deep in the snowpack. Human-triggered avalanches are most likely in recently wind-loaded terrain but are also possible in areas that are more sheltered from the wind. 

Tragically, a snowmobiler was killed in an avalanche Wednesday in the Baker Creek drainage of the Smoky Mountains. We extend our heartfelt condolences to the victim’s friends and family.

Problemi valanghivi

  • Wind Slabs

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

    You’re most likely to trigger a wind slab avalanche in areas loaded by the recent moderate to strong SW-S-SE wind. Yesterday, the Titus Peak weather station near Galena Summit reported several hours of 35 mph SE wind with gusts in the 40s. On Wednesday, I observed freshly forming wind slabs in the Boulder Mountains. Looking across to the Smokys and over into the southern Sawtooths, it was apparent that the wind was having the same effect. 

    Wind slabs will be thicker and more widespread as you climb into upper elevation but will also be found at middle and even some exposed lower elevations right down to the valley floor. Be alert to obvious signs of instability such as nearby recent avalanche activity or cracks shooting from your boards or sled. Wind-drifted areas are also where you’re most likely to trigger the larger, more destructive persistent slab avalanches that are described below.

  • Persistent Slabs

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

    Although snowfall has slowed recent wind-loading will keep the snowpack on edge. You’re most likely to trigger a persistent slab where a stiff wind-loaded slab sits over weaker snow at the ground. Yesterday, we found this snow structure during our site investigation of the fatal avalanche that occurred Wednesday in Baker Creek. 

    Although wind-loaded areas are more hazardous, don’t let your guard down on apparently sheltered slopes. Recent strong wind and settling within the heavy load of storm snow has created a cohesive slab in many locations, including low elevation terrain. 

    A break in the weather on Wednesday allowed SAC staff and public observers a chance to document dozens of very large avalanches near Copper Mountain and the Sawtooths. Large avalanches were also seen near Galena Summit and in the Soldier Mountains. Avalanches failing on persistent weak layers can break wider than you expect, spanning terrain features and changes in aspect. These slides may be triggered remotely—from gentle terrain above, beneath, or to the sides of steeper slopes.

Avalanche Discussion

On January 15th, 2020, a snowmobiler was caught and killed in an avalanche in the Baker Creek drainage, approximately a half-mile northeast of Baker Lake. We visited the site yesterday to collect data on the avalanche. This video contains preliminary information collected during the site investigation; a full accident report will be published soon.

The avalanche released at an elevation of 9200 feet on a south-facing, wind-loaded slope. The slab broke 2-3 feet deep, 250-300 feet wide, and ran just over 600 vertical feet. The slope angle of the start zone was around 33 degrees, but the slope steepened significantly below the fracture line. The avalanche was triggered from lower on the slope, well below the crown line of the avalanche, and released on a persistent weak layer of faceted snow in the middle to lower snowpack. The avalanche debris range from 3-8 feet deep.

The lack of any real break from wind-loading will continue to add stress to weak layers buried near the middle and base of the snowpack. The avalanche danger will remain elevated until this prolonged stormy weather lets up giving fresh wind slabs time to heal and the widespread, underlying persistent weak layers a chance to adjust to the new load.

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