Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

Alpine
4 · High
Treeline
4 · High
Below
2 · Moderate
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Highlights

Yesterday's very strong winds and continued snowfall has formed soft to hard slabs on a variety of aspects and elevations. Additional snowfall and strong winds that will occur today will add to this surface slab problem and will also further load deep weaknesses in the snowpack. At the mid and high elevations, natural avalanche activity will be likely involving both the new and the deep layers. Backcountry travel is not recommended in these areas. At lower elevations, identify steep terrain features where loading has occurred and be aware of the run out zones of large avalanche paths. A deep slab is reported to have occurred yesterday in Drew's Slide to the south of the Jackson Hole Mountain Resort.

Avalanche problems

  • Wind Slabs

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

    Very strong south to southwest winds and new snow have formed wind slabs in steep leeward terrain at all elevations. These slabs lie upon recent density breaks within the upper portion of the snowpack and could have depths of up to three feet. They could release naturally today, particularly at the higher elevations as they are further loaded by new and blowing snow and will sensitive to backcountry travelers all day.

  • Deep Persistent Slabs

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

    Approximately ten inches of moisture has fallen since the start of the new year. Dangerous, deep, hard slabs could fail from the impact of a triggered wind slab or possibly by the weight of a single person hitting a weak spot on a slope. These slabs could fail on two distinct weak layers. The higher layer was buried at the start of the new year and could release with depths of two to four feet at the upper elevations and with depths to two feet at the lower elevations. This buried weak layer lies on a variety of aspects and is made up of surface hoar, buried faceted snow, and on south facing aspects, crusts. A deeper pronounced weak layer was buried on November 25th. This hazard is limited to north facing terrain at 8000 feet and as elevation increases, involves more aspects. At 9500 feet west, north and east facing slopes can have this weakness. If triggered, slabs involving this layer could have depths to six feet.

Avalanche Discussion

A weak wave will bring several inches of snow to the higher elevations of the Teton Range, Togwotee Pass and the northern portion of the Greys River area overnight. On Wednesday skies will be partly cloudy to mostly clear under a lighter westerly flow. Winds will gust from 30 to 45 on the peaks tonight and decrease to 25 to 30 miles per hour during the day. Temperatures in the mountains will remain in the single digits and teens. At the mid and upper elevations freshly formed wind slabs one to three in depth can be human triggered on steep slopes. Very dangerous deep persistent slab avalanches 4 to 8 feet in depth are also a huge concern. These killer avalanches could be triggered by the weight of a single person or release naturally in response to continued loading by tomorrows winds. Smaller slab avalanches 1 to 3 feet in depth could be human triggered on steep wind loaded terrain features at the lower elevations. The general avalanche hazard is expected to be considerable above an elevation of 7,500 and moderate below that elevation. Expert terrain assessment skills and conservative terrain choices are essential for safe travel in avalanche terrain.

Regions covered