Bollettino valanghe

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Human triggered avalanches are possible at all elevations in the Greys River Zone today. Areas where the wind has stiffened the new snow into slabs that overlie slick crusts and buried weak layers are the primary concern. Pay attention to signs of instability such as audible collapsing of the snowpack and cracking within wind affected snow. Use your shovel to dig into the snowpack and determine whether weak snow or crusts are present below the new snow on the slopes you plan to ski or ride. 

BTAC Foundation is holding a raffle to support the work of the avalanche center.  You could win seasons passes, avalanche course, skis or a day heli-skiing. Check here for details.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    The Greys picked up 20 to 30 inches of snow from February 19-23. Westerly winds prevailed at the beginning of the storm cycle but veered to the North and eventual the East by the end of the cycle. This has resulted in wind slabs that are generally 12-16 inches deep on a variety of aspects, but could be up to 2 feet deep in favored locations. On the northern half of the compass these slabs are failing on a density change within the new snow or on the new snow/old snow interface (Feb 18). On the southern half of the compass these slabs are failing on a slick crust at the new snow/old snow interface (Feb 18). These slabs could be both soft (4f) and hard (1f). Wind pressing from easterlies at the end of the storm as stiffened slabs on unusual aspects. 

    Pay attention to signs of instability such as cracking within wind drifted snow. 

  • Persistent Slabs

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

    Weak faceted snow and slick crusts exist at both the new snow/old snow interface (Feb 18) and lower in the pack. The Jan 26 crust/facet and surface hoar layer is buried 60-80 cm below the surface of the snow at the upper elevations. It is unknown how reactive this layer is. Triggering avalanches from a distance (remote triggering) is possible. 

    Pay attention to signs of instability such as audible collapsing of the snowpack. 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. 

Avalanche Discussion

The Greys River Zone has picked up a trace to 1 inch of snow in the last 24 hrs, with most of that snowfall occuring in the early morning hours yesterday. A closed low off of the California/Oregon coast will spin up small amounts of moisture into western Wyoming today in a SW flow. Scattered snow showers are expected today with some possible windows of sunshine in the afternoon. Winds will be out of the SW gusting into the 30s. Temperatures will reach the upper teens on the peaks and mid twenties in the valleys. 

Recent avalanches have been observed at all elevation bands, with failure planes either within the new snow or at the new/old interface. However, avalanches that likely failed on deeper persistent weak layers have been observed in some locations at the middle and lower elevation bands. Wind slabs are present on a variety of aspects and elevations. 

The snowpack structure varies throughout the Greys River Zone. The Palisades, Salts, and Snake River core have depths and structure that is akin to that of the Tetons (think deeper, stronger). As you move south and east towards the Wyoming range snow depths become more shallow, and the effect from arctic air masses more pronounced (similar to Togwotee). A great deal of uncertainty revolves around the structure and stabilty of the more remote areas within the Wyoming range due to a lack of observations. 

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