Avalanche forecast

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Extreme winds and  8-10" of new snow in the past 36 hours created dangerous conditions that will require careful assessment and route-finding today.  The threat of natural avalanches, such as occurred yesterday, has passed but widespread wind slabs combined with buried weak layers make large avalanches possible today.  Dig pits, observe snow surfaces for signs of wind loading and find your route cautiously if you brave the extreme cold to travel in the mountains today. Steep rocky terrain below cliffs are areas worth avoiding.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Due to the extreme winds, you'll find wind slabs up to a two feet thick in deposition areas below 8,000'.  These may still be sensitive to triggering today. Above that elevation, slabs are more likely to be stubborn to triggering but will be much larger; two to four feet, maybe more in isolated areas. You'll find a mix of scoured terrain, sculpted snow surfaces and large drifts at most all elevations and aspects today.Wind slabs also exist at middle and lower elevations and though they are smaller, they are also more likely to be sensitive to triggering. By nature, the harder the slab, the more likely it is to crack a long distance from you rather than underfoot so check for hollow sounding snow and consider the extent of the wind slab above or beside you.  

    (12/21/2022)

    We triggered two small slides on test slopes (N and SW aspects) on the Squaw Creek trail in the northern Greys forecast area.

    Photo: Frank Carus

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–3

    Leeward areas may contain slabs 2-4' thick, along with cornices that could fail under your weight.  The slabs are sitting on weak layers of buried, faceted snow which have plagued our snowpack since late November and have only recently begun to gain strength.  The new snow and wind slabs may tip the balance back towards instability.  Particularly troublesome slopes are those that have avalanches previously and reloaded (generally SE, E through N aspects),  solar aspects with a thin snowpack comprised of crusts and facets and steep rocky slopes. The Cow in the Woods slide yesterday morning in Hoback canyon is a good example of the very large avalanche that this layer could still produce. 

    (12/21/2022) Cow and Calf of the Woods debris piles after full mitigation efforts

Avalanche Discussion

Wind speeds on the summit of Rendezvous Peak yesterday morning hit 96 mph. Signs of extreme wind were everywhere with downed trees, sastrugi and debris scattered around even at valley locations. High snow desntities refleted the high wind as turbulence aloft began rounding snowfalkes before they even hit the ground.  Snow quickly formed slabs where none existed before with some natural avalanches observed even in the poor visibilty. Intentional human triggered avalanches were reported as well. 

Very cold temperatures are likely to sap these slabs of energy today and it seems likely that the number of human triggers in the mountains today will be small given the very cold temperatures. By the middle of the day, it is likely that conditions wil more accurately fit a the definition for moderate avalanche danger. The recency of the loading however, combined with the persistent slab problem creates the sort of conditions that will require very careful route-finding to figure out the intersection of these avalanche problems. 

Regions covered