Bollettino valanghe

Tetons

Bridger-Teton Avalanche Center
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Pericolo valanghe

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

The hazard will be increasing at all elevations today. Rising temperatures and rapid loading will create unstable conditions. Dense surface slabs are forming upon persistent weak layers comprised of buried surface hoar. These persistent weak layers are a game changer. Small slab avalanches were unintentionally triggered by several different skiers yesterday. These events included slabs that were triggered by the 3rd and 4th skiers on a slope and an event that occurred on a low angle slope. All of these events likely involved buried surface hoar. Due to the spacial variability of buried surface hoar suspect slopes or portions of suspect slopes may be remotely triggered, may be triggered after being crossed multiple times or may be stable. The likelihood for humans to unintentionally trigger slab avalanches will be increasing and is problematic. As these slabs gain depth and volume the potential for serious injury will increase. Natural avalanche activity is possible today.

Problemi valanghivi

  • Persistent Slabs

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

    Southwest winds have formed dense surface slabs on layers of surface hoar that were buried on January 16, 11 and 2. These buried persistent weak layers are potential failure surfaces for slab avalanches. At the mid and upper elevations these surface slabs will become increasingly sensitive to human triggers and are likely to fail on the January 16 or 11 layers with depths up to two feet. Some potential may exist for these slabs to step down to the January 2 layer with depths to three feet. Shallow wet loose slides and pockets of dense or wet surface slab up to a foot deep are possible in steep terrain at the lower elevations.

Avalanche Discussion

The moist west flow will continue to bring periods of snow to the region with the heaviest snowfall expected in the Teton Range. Lesser amounts are expected on Togwotee Pass and over the Salt River and Wyoming Ranges. The snow will decrease in intensity but periods of light snowfall should continue through Monday. Winds will be west to west-northwest at speeds of 25 with gusts to 40 miles per hour overnight and slowly decrease to speeds to 15 to 20 miles per hour by Monday evening. Temperatures will drop into the teens and 20s. The persistent weak layers of surface hoar covered by the recent new snow are a game changer with respect to the short and long term stability of our snowpack. Due to the spacial variability of the buried surface hoar suspect slopes or portions of suspect may be remotely triggered, may be triggered after being crossed by multiple persons or may be stable. Cooler temperatures and decreasing snowfall will decrease the sensitivity of these slabs to humans triggers, however today's additional moisture have increased the size and density of these avalanches. While the likelihood of triggered is expected to decrease the potential for humans to unintentionally trigger a slab avalanche with severe consequences is significant. The general avalanche hazard is expected to be MODERATE on Monday, however the assessment of this hazard is inherently problematic and therefor unintentionally triggered slab avalanches are possible with potentially severe consequences.

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