Avalanche forecast

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Human triggered avalanches remain possible at the middle and upper elevations today. Soft slabs that are around a foot thick will be reactive to human triggering, especially on steep, unsupported slopes that receive direct sunlight. These soft slabs could potentially trigger larger avalanches failing on buried weak layers. Pay attention to signs of instability such as cracking within wind drifted snow and minimize exposure time in and around steep, sunlit slopes. 

Avalanche problems

  • Wind Slabs

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

    Soft wind slabs that average 1-2 feet in thickness will be reactive to human triggering in specific locations throughout the middle and upper elevations. Humans are mostly likely to trigger these slabs in steep, unsupported terrain features that are exposed to direct sunlight. Terrain features could include steep ridges and spines, couloirs, and slopes in and around cliff bands. 

    These slabs are the remnants of the most recent atmospheric river event that occured from March 14-16. Winds started off strong and southerly, and eventually died off and veered all the way to the NNE. Snowfall totals ranged from 12 to 16 inches with around 1.7 inches of SWE. Temperatures cooled into the single digits after the storm pass, helping to settle and condense the new snow. This has resulted in uniform slabs throughout the terrain that are on average 1 foot thick and 4F in hardness. 

    Loose snow and Cornices: loose snow avalanches (both dry and wet) could pose a threat to individuals in very steep sunlit terrain at all elevations today. Cornice collapse could trigger unusually large avalanches for the given conditions.

    (3/16/2023)

    12-16" soft slab on steep 40 degree slope. Failed on new/old interface on melt freeze crust. 

    Photo: Drinkard

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    Lingering beneath a hard slab (and beneath new snow or wind slabs) lies weak layers buried 2-3’ down. The Feb 18th layer is our main concern due to an increase in avalanches in the Wyoming Range(Shepard Creek, Hoback Peak). The Greys River forecast zone has a diverse snowpack with stark differences between each individual mountain range. The Salt and Snake River Ranges have not seen the uptick in recent avalanche activity or propagating results in stability tests. Our main focus continues to be on the heightened avalanche danger in the Wyoming Range. Increased loading from this  storm will add stress to these weak layers, especially in wind loaded terrain. Reported avalanches have been triggered remotely, and this potential will remain today. Avoid slopes over 30° and understand that large avalanches can be triggered remotely from gentler slopes above, below, or beside steep slopes.

    (3/17/2023)

Avalanche Discussion

No new snow for the Grey's River zone this morning. Today's forcast is for sunny skies with light and variable winds in the alpine. Temperatures could reach the mid 30s in the valleys and 20s on the peaks.

Persistent slab avalanches were triggered by riders in the Wyoming Range yesterday. Recent human triggered avalanches involving the most recent storm snow were observed on Ferry Peak 2 days ago. These avalanches were soft slabs averaging about a foot in depth (up to size 2) and they occured on aspects ranging from East through South. Older avalanche activity involved wind slabs and persistent slabs that were size 1-2, including some avalanches that were remotely triggered from afar.  Check out the YouTube field report from Blind Bull from Monday the 13th for more on this persistent weak layer concern.

Current snow surfaces are composed of new snow and sun crusts. Much of the new snow has been wind affected at the upper elevations and sun crusts will continue to develop today. The new snow/old snow interface is buried about a foot deep on most aspects. The Febuary 18 interface is buried 1-3 feet deep (depending on aspect and elevation). Shallow areas within the Wyoming Range harbour well developed depth hoar and weak basal facets. 

 

 

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