Bollettino valanghe

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

New snow combined with sustained strong shifting wind created firm, cohesive slabs that were reactive to human triggering yesterday. These slabs will also stress buried weak layers where the potential exists to trigger a much larger avalanche remotely from gentler terrain above, below or beside steep slopes (as seen recently in the Wyoming Range). Use careful judgment and avoid wind loaded terrain while looking for obvious signs of instability such as cracking, stiffened surfaces and drifts.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Yesterday the zone experienced some of the stronger winds we have seen all winter. Wind speeds were 30-50 mph during peak storm with gusts to 70 mph, finally decreasing by this morning. Wind direction shifted yesterday from south to west. Expect to see reactive wind slabs of varying depths 1-2 feet with up to 3 feet possible in specific terrain. These slabs will be found in the middle and upper elevations across an array of aspects due to shifting wind direction. Pay attention to unsuspecting terrain where these slabs could be found in uncommon areas. Use careful assessment in exposed terrain in the middle and upper elevations, especially above the treeline. 

     Partly sunny skies are forecasted today. Monitor the influence of the sun on new snow as warming could increase reactivity on solar aspects. 

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    Lingering beneath a hard slab lies weak layers buried 2-3’. The Feb 18th layer is our main concern due to an increase in avalanches in the Wyoming Range(Shepard Creek, Hoback Peak). The Greys zone has a diverse snowpack nestled 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 is on the heightened avalanche danger in the Wyoming Range. Increased loading from this recent 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.

    (3/7/2023)

    This avalanche was triggered remotely by the skiers on the rib well to the right of the start zone.

    Photo: Dan Janjigian

Avalanche Discussion

Life in the snow globe continues as the atmospheric river storm produced up to 10-12 inches of snow favoring certain locations in the Greys. Storm slabs were reactive yesterday, but cold temperatures last night with settlement should decrease their reactivity. Our attention is focused on the middle and upper elevations where howling winds have formed reactive wind slabs. Wind speeds of this intensity have not been common this season, with a 24 hour total of over 800 mph. Which means a whole lot of wind! Wind slabs will be the primary concern while you are traveling in terrain today. Exposed terrain will contain a mix of wind scoured and loaded slopes. Seek powder riding in that sheltered terrain while these wind slabs are still touchy and reactive today. The best snow will likely be in the safest locations. 

Our focus shifts to the persistent slab problem found in the Wyoming Range. This area has experienced numerous large avalanches on the Feb 18th weak layer. Rapid loading of snow yesterday will stress this layer. Other areas are not as dangerous, as the Feb 18th layer is trending towards dormant in the Snake and Salt River Ranges. Unfortunately, we don’t want to count our cards quite and neglect the possibility. Use careful judgment if recreating in the Wyoming Range as the combination of wind slabs with a persistent slab is a deadly combo. 

 

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