Bollettino valanghe

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
Open full map
Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Large differences in the snowpack across the Greys has created a variety of avalanche conditions including weak layers buried 2-3 feet deep found in the Wyoming Range where triggering a large avalanche is possible. This is unlikely in Salt and Snake River Ranges. New snow and wind today could form small, fresh slabs by the afternoon across the whole area. Monitor the amount of snow accumulation during the day while looking for signs of instability in the new snow such as cracking, stiff slabs, and drifts.

Problemi valanghivi

  • Wind Slabs

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

    Stubborn, isolated pockets of firm slabs above weak surfaces could still be found in upper elevations, mainly above treeline or near cliff features. Otherwise, you will find mostly stable avalanche conditions until the late afternoon as 4-6” of new snow with light to moderate SE to SW wind forms fresh, small slabs. This new snow will fall on a variety of old surfaces including facets, hard windpack, and crusts. Monitor the amount of new snow (especially if snowfall exceeds forecasted totals) and how well it bonds to these old surfaces to track instability in the coming days as snow continues this week. Small storm slabs failing on the old/new interface less than 6” deep could be possible by this afternoon as temperatures increase creating upside 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

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

    Weak layers buried 2-3 feet deep are still haunting the snowpack across all aspects and elevations in areas with a shallower snowpack such as the Wyoming Range. Drastic differences lie in the snowpack between the Salt, Snake, and Wyoming Ranges. These weak layers are not as concerning in the Snake and Salt River Ranges based on observations in snow pits and overall avalanche activity. The main concern in the Wyoming Range is the Feb 18th layer composed of crusts and facets. The recent warming trend has not been sufficient enough to stabilize this layer. Triggering a large avalanche remains possible on steep slopes over 35°, especially on wind loaded terrain and during rapid warming in the afternoon. Snowfall this week will add stress to these buried weak layers potentially increasing their sensitivity. 

    (3/17/2023)

Avalanche Discussion

Goodbye Sun, Hello Snow

Today we transition from one of the longer periods of clear and sunny conditions we’ve seen all winter back into the snow globe. This week we saw a prolonged cycle of 12-16” deep human triggered wind slab avalanches. These wind slabs were reactive due to the poor new/old snow interface. There has been discussion about whether this is now a persistent slab problem. This is unlikely due to the large daily temperature fluctuations helping bond this interface. Yesterday was the first day of no reported avalanches, with observations confirming this interface is trending stable. Isolated pockets may still be found in the alpine that holds a unique, spatially variable snowpack where this interface is still sensitive. Otherwise any avalanche concerns today will be focused on new snow. Forecasted snowfall totals during the day should be less than 6” with fairly calm winds. Snowfall will continue this week increasing the avalanche danger. The variety of snow surfaces created by strong solar radiation, winds, and cold nights has created poor interfaces for this new snow. Today is a good day to test the reactivity while snow totals are low by performing hand shear tests and finding small test slopes. Figure out the sensitivity and distribution of this interface across different aspects to set yourself up for the coming week of powder riding. 

*Remember that persistent weak layers still exist in areas of the Greys that contain a shallow snowpack including the Wyoming Range. 

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