Avalanche forecast

Togwotee Pass

Bridger-Teton Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
No rating
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Highlights

Avalanche danger will increase by the late afternoon as increasing westerly wind forms fresh, reactive slabs primarily in the upper elevations. Wind loaded terrain will also add stress to weak layers buried 2-3 feet deep where triggering a wind slab could step down and trigger a larger, more destructive avalanche. Steer clear of terrain where these avalanche problems overlap and seek less consequential slopes sheltered from the wind. 

Avalanche problems

  • Wind Slabs

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

    8-10 inches of the snow over the last 48 hours combined with shifting south to west wind has formed slabs up to 12 inches deep on wind loaded terrain in the upper elevations. Increasing wind in the afternoon will form newer and more reactive wind slabs. Triggering avalanches will be more likely the higher you travel in elevation and into more open/exposed terrain to the wind. Look for signs of instability including stiffened snow surfaces, shooting cracks, or large pillow/drifts formed. Variable new to old snow interfaces could make wind slabs more reactive on specific terrain. 

    Watch for dry loose avalanches on steep terrain over 35° if you find forecasted high end snow totals around 4” by the end of the day. Recent snow has fallen on a variety of different snow surfaces that vary by aspect. Perform quick hand shear tests and assess how the recent snow is bonding to old snow surfaces.

    Shooting cracks provide a clear indication of unstable snow on wind loaded terrain. 

    Photo: Alex Drinkard

  • Deep Persistent Slabs

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

    Weak layers are most likely to be triggered where the slab is 2-3 feet thick and on very steep slopes over 35 degrees. Triggering a wind slab increases the possibility of an avalanche stepping down to buried weak layers. Signs of instability such as cracking, collapsing, or recent avalanches may not be present before triggering a dangerous avalanche. Multiple tracks on a slope do not indicate stability with this problem type. Suspect terrain includes very steep, rocky, and/or wind affected slopes where thin spots exist making it possible for humans to impact buried weak layers. 

    Persistent slab avalanches are capable of propagating widely across or up a slope. For this reason, it is not out of the question to trigger a larger hard slab avalanche with depths over 5 feet as a result of hitting a thin, shallow portion of the slope. Heavily wind affected slopes are where these avalanches could break deeper, such as this very large persistent slab on Lava Mountain that occurred on February 10th.

    The last human triggered persistent slab avalanche occurred on March 2nd in terrain similar to this.

    Photo: Dakota Richardson

Avalanche Discussion

Windy Afternoon

Avalanche danger will increase throughout the day in direct correlation to increasing west/southwest wind. Sustained wind exceeding 20 mph with gusts in the high 30s will develop around noon. We could encounter the high end of Moderate danger rating by the late afternoon/evening. If you encounter increasing wind intensity  and observe visible snow transport, seek more sheltered terrain as small wind slabs will be most reactive while they are actively forming. Larger wind slabs will be possible by the late afternoon. 

Recent snow has trended more stable since the beginning of the storm where snow came in warm and wet easily failing on previously formed crusts on southerly aspects. Cooling temperatures over the last 36 hours have helped lock up the recent snow on southerly aspects. The big question is how northerly aspects are bonding. Faceted surfaces prior to the storm have been identified on sheltered northerly aspects. These new to old snow interfaces may take longer to bond. Use careful snowpack assessment on northerly aspects where this interface exists.

If you see avalanche activity or would like to help inform our forecasts, please consider submitting an observation HERE. You can also text what you see to us at 307-264-3050.

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