Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Weak layers (sugary facets, surface hoar, and/or crusts) are buried beneath slabs up to 3 feet thick. Human-triggered avalanches remain possible on both sunny and shady aspects. The middle elevations, particularly around 7,500 to 8,500 feet, have more continuous weak snow layering. Assess the snow you are riding on. Conservative travel practices are necessary on all steep slopes, including treed areas in the middle and low elevations.

Avalanche problems

  • Persistent Slabs

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

    Areas of faceted snow, crusts+facets, and buried surface hoar are widespread across this range and concentrated in the low to middle elevations. Field observations are consistently finding unstable conditions in snowpits, with failure and full propagation continuing several days after any new snowfall.  Add a data point to your assessment of the snowpack by digging and moving one at a time, both on the uphill and downhill, in avalanche terrain. 

    (12/6/2022)

    Results from avalanche mitigation at Snow King: 16” crown on N aspect at lower elevation

    Photo: Jake Hutton/ Bennette Timmerman SnowKing Ski Patrol

Avalanche Discussion

Nearly every snowpit in the observations over the past several weeks has continued to propagate at the middle and upper elevation bands (around 7,500 to 10,000 feet). These areas include frequented areas like Glory Bowl and the sidecountry terrain of Jackson Hole Mountain Resort. The results of avalanche mitigation at Snow King yesterday also made me add back in the lower elevation band. The snowpack structure is poor at low elevations, and smaller snowfall amounts are capable of tipping the stability scales.

 Areas of faceted snow, crusts+facets, and buried surface hoar are widespread across this range and concentrated in the low to middle elevations. Some of these snowpack layers are also known to persist predominantly in the middle to lower elevations, dependent on the mountain range.  These pits are failing on a variety of weak layers found on both southerly and northerly aspects, and primarily hold a mix of thicker layers of small facets, and/or surface hoar.  A common theme appears to be high strength in extended column tests (high # of taps before failure) and fair structure (not the worst, not the best).  The longer these problems linger, the more I view the terrain I approach with caution. Time heals (sometimes), but until then, these results are spooky and far trickier than if there was more obvious instability and easier failure. The slab above these layers is significant and thick-- implying a low probability but high consequence scenario. Communicate with your partners about what you are seeing in the snowpack and talk about the terrain around you and above you. 

Additionally: This zone received 3-7 inches of snowfall than was predicted with moderate to strong winds at upper elevations. Wind slabs that formed during this storm have likely stabilized, but a few may remain sensitive to your weight. Importantly, they are also adding load to the weak snow underneath.  

Regions covered