Bollettino valanghe

Tetons

Bridger-Teton Avalanche Center
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Pericolo valanghe

Sat
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The avalanche danger will increase throughout the day as new snow and wind conspire to build fresh wind slabs at the middle and upper elevations. These fresh wind slabs could stress buried week layers that are 1-2 feet deep on southerly aspects at all elevations. Utilize lower angle terrain features on southerly aspects and pay attention to signs of instability such as cracking within wind drifted snow. 

Problemi valanghivi

  • Wind Slabs

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

    Fresh WIND SLABS that are reactive to human triggering will be located near ridglines and start zones in the lee of westerly flow. These slabs will mostly be soft (4F) and generally have maximum depths of 1-2 feet. They could be deeper near Grand Targhee. 

    Shallow STORM SLABS will start to build today on top of a layer of well preserved stellars in protected areas. If snowfall rates exceed  1 inch per hour this morning these slabs could fail naturally. 

    Old stubborn WIND SLABS that are 1-2 feet thick linger in isolated terrain features on a variety of aspects in the alpine. 

    DRY LOOSE sloughs could run far and fast with all of the recent low density snow.

  • Persistent Slabs

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

    The Feb 18 crust is located 40-70 cm down from the surface of the snow on the southern half of the compass. This layer is reacting in the moderate to hard range in stability tests and has shown a propensity to propagate a fracture, especially at the middle and lower elevations.

    The Jan 26 crust is located about 30 cm below the Feb 18 crust and is considered dormant at this time. 

    When dealing with a persistent slab problem your best course of action is to dig a hole and use snowpack instability tests.  With the Feb 18 layer being relatively close to the surface (especially at the middle elevations), you can utilize pole probes and hand shears to track the signature of the layer. 

Avalanche Discussion

Grand Targhee picked up another 10 inches of 4% snow last night, JHMR got 6-9 inches up high, and Surprise picked up around 6 inches. The middle and lower elevations picked up 2-4 inches and low temps were in the teens in the valleys. Winds backed from the WNW yesterday afternoon to the WSW with averages around 20 mph and 532 total miles at Rendezvous.

Recent avalanche activity has been confined to small soft slabs in the Tetons, but natural avalanches have been observed on the lowland buttes and sage brush slopes surrounding Jackson Hole. 

The storm from Feb 19-26 blanketed the Tetons with a relatively cohesive slab of snow that is 1-2 feet thick. Since that time incremental loading has left the Tetons with right side up powder in sheltered areas and wind slabs in exposed areas especially at the uppermost elevations. The main layer of concern is the Feb 18 crust/facet combo that is buried 40-70 deep on the southern half of the compass. On northern aspects failure planes are suspected to be within the new snow especially in wind affected areas. 

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