Avalanche forecast

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Dangerous avalanche conditions exist today and human triggered avalanches are likely. Since Thursday morning, some areas of the forecast area have recieved approximately 3 feet of new snow. Steep terrain at the mid and upper elevations, where wind enhanced the formation of cohesive slabs will be the most sensitive to recreational skiers and riders. At lower elevations, slides could be triggered in wind loaded areas or in other very steep terrain where the snowpack has not yet adjusted to the recent, rapid loading.  Any steep terrain is suspect today and conservative terrain selection is the best way to avoid an avalanche accident.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Approximately 3 feet of recent snow, containing over 2 inches of water, and moderate winds that were generally from the west/northwest but are now backing to the south have loaded steep avalanche starting zones. Although the likelihood of natural activity is decreasing, snow is to continue to fall this morning and these slabs remain sensitive and can be triggered by a single person. This could occur while approaching a slope or once one is exposed and mid-slope. Slabs could be shallow, failing on denstiy changes within the new snow or fail on the storm interface buried on Thursday to a maximum of 5 feet at the highest elevations and in major avalanche paths. At low elevations these slabs may have not have apparent wind loading but they could still be triggered in very steep terrain to depths of 2 feet. Be aware of steep banks and road cuts where small slides can have severe outcomes. 

    (1/28/2023)

    Teton Range: Diamond showing crown depth of a remotely triggered avalanche on 25 short. This avalanche failed on a thin layer of buried near-surface facets under recent snowfall. 

    Photo: Antonioli

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–3

    At the mid and upper elevations, deeply buried weak snow layers persist. Although triggering one of these events is unlikely, if triggered they will be very large and destructive hard slabs. Today these slabs are most likely to fail following the triggering of a large wind slab but cornice failure or a group of people impacted a thin and weak spot on a slope could also cause their release.  Looking for signs of activity involving this layer during the last two day's rapid loading will help determine how long this problem may remain in the forecast. 

Avalanche Discussion

The rapid loading that occurred during this storm event is uncommon. Approximately three feet of snow fell in the Wyoming range and more is suspected to have fallen in the Snake River Range. On Friday, the snow 6-8% snow was falling on lighter snow, surface hoar, near surface facets and firm surfaces such as sun-crusts and wind pack. At first, rapid snowfall resulted in widespread natural activity with relatively low volume debris  but by Saturday morning, the amount of new snow accumulation was becoming more problematic. Slabs were upside down and the potential to iclude higher volumes of snow was increasing. Very steep terrain at low and mid elevations were releasing and steep banks impacted roadways in canyons, towns, and on Teton Pass. Many avalanches were reported to the avalanche center although the bulk of the backcountry was obscurred and recreationalists generally backed off onto lower angle slopes. Little activity was reported in the southwest trails area, likely due to limited visibility and people stay out of the highest terrain.  Avalanche conditions today will not be as blatantly obvious or sensitive and deserve more thought and respect.  Although some slopes may release upon approach, most slabs will have become more stubborn from settlement and cold temperatures and slab initiation may not occur until on the steepest part of the slope or on a convex rollover mid-slope. Use caution and avoid known avalanche paths as lower angle terrain is the best way to avoid an avalanche accident today. 

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