Boletín de aludes

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Peligro de aludes

Mon
Alta montaña
3 · Notable
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Multiple avalanches have been triggered over the last three days on weak layers buried 1-3 feet deep across all elevations and most aspects. These weak layers have increased in reactivity due to warming temperatures and wind loading, which will remain reactive today. In addition, new snow accumulation today with increased strong S/W wind will stress buried weak layers and form fresh wind slabs. Use careful assessment of terrain and dig down to test weak layers before riding consequential terrain. 

The next storm system moves into the area today and tonight. Forecasted snowfall totals up to 8”  by this evening with strong SW wind will increase avalanche danger throughout the day. 

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–1.5

    Fresh wind slabs near ridgelines and exposed terrain have been formed recently less than 12 inches deep. Wind direction has varied across the zone, with S/SW wind in the northern portion and W wind in the southern portion. These winds have deposited snow onto leeward terrain, which will increase in reactivity with snowfall during the day forming new slabs. Areas with wind slabs could also increase the chance of triggering a persistent slab in the middle and upper elevations. Look for obvious signs of instability such as cracking, stiffened surfaces, and drifts. 

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1.5–2.5

    Weak layers buried on Feb 18th have increased in reactivity over the last several days with wind loading in the upper elevations and warm temperatures with solar influence in the low/middle elevations. Multiple D2 avalanches have been triggered on this new/old snow interface. Soft and hard slabs range from 1-2 feet across all elevations, with depths up to 3 feet in the upper elevations in wind loaded terrain. Avalanches have been triggered on all aspects with the highest concentration from South to East This new/old interface consists of facets and crusts. Additional snowfall today will add stress to weak layers, especially where fresh wind slabs form.Use careful judgment as these weak layers remain reactive today.

    Deeper weak layers still remain a concern, primarily the Jan 26th layer buried 2-4 feet deep. These layers have been most reactive in the southern portion of the zone in the low and middle elevations. These avalanches could be triggered remotely from above, below, or beside you. Three days ago an avalanche in Poker Creek failed on these deeper weak layers, unfortunately resulting in a fatality. 

    Pay attention to signs of instability such as audible collapsing of the snowpack and monitor the effects of new snow and wind. Your best line of defense against a persistent slab problem is to dig a snowpit in a representative location and perform some stability tests such as an Extended Column Test.

     

    (2/24/2023)

    Poker Creek fatality from a persistent slab avalanche. 8100' NW aspect

Avalanche Discussion

The last several days have seen numerous human triggered avalanches across all elevations and most aspects. This may come as a surprise since we haven’t seen any new snow accumulation. But, those other red flags play a significant factor with warming temperatures and increased wind recently. Remember that any changing conditions requires you to dial back terrain choices. This last storm cycle changed the structure of our snowpack, forming cohesive slabs with propensity to propagate above buried weak layers near the base of the snowpack in the low and middle elevations. Thus, avalanches have been triggered in areas we previously haven’t seen all winter. Previously unsuspected terrain may catch you off guard. Don’t let this happen. 

Today the next storm cycle will approach our Forecast Area. Avalanche danger will increase throughout the day. The amount of avalanche activity combined with more snow and wind should raise the hair on the back of your neck. Use careful decision making and monitor the new storm as avalanche danger increases. 

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