Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

Fri
Alpine
1 · Low
Treeline
1 · Low
Below
No rating
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The avalanche danger is Low at the mid and upper elevations. It is very unlikely but not impossible to trigger an avalanche. Extreme terrain, near cliffs or rock bands, and unsupported slopes could be the exception. Buried weak layers under thin spots in the slab may be easier to trigger in locations such as those.  Low elevations lack sufficient snow depths for avalanche concerns. 

Avalanche problems

  • Persistent Slabs

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

    Weak snow formed during a prolonged dry period in November lies buried one to three feet below the surface of the snowpack on shady slopes with a northerly tilt (W-N-E aspects).  Observations of that weak layer in pits has shown that it has remained dry, loose and largely intact, pretty much since it's formation, despite settlement that has stiffened and strengthened the overlying slab. This strengthening of the slab and some subtle changes in the deeper stratigraphy has reduced the number of obvious alerts to its existence such as whoompfing and shooting cracks but has not reduced its tendency to propagate a crack in stability tests, albeit stubbornly. 

    If venturing into very steep terrain, digging or probing in the snowpack can help you determine where and how deep lies the weak faceted snow. You'll find lots of tracks on steep slopes and generally strong snow. Taking the time to dig is good practice and may be the reality check that you need before center-punching  a consequential slope. Skiing or riding on lower angle slopes is a more certain method to avoid triggering what could be a hard slab avalanche up to three feet thick. 

    Avalanche on the recent (12/24) snow interface in the Big Holes on an east aspect around 8,400 feet. 

Avalanche Discussion

At risk of sounding like a nag, low danger doesn't mean no danger. As folks continue to step out into steep terrain, remember that this brittle slab still has thin spots and still has a weak layer beneath. I wouldn't discount a confluence of risk factors, like thin snow near a rock plus solar heating, to weaken the slab and increase the odds of trigging something, given the sunshine and calm winds today and tomorrow. Unlikely? Yes. Impossible? No. 

Ferreting out soft, untracked snow between old, refrozen tracks is a challenge now. As is behaving with just the right amount of restraint. The weak layer may be heading towards dormancy but we aren't really there yet. The weather forecast doesn't give much reason to expect that to change in the next week or so. 

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