Bollettino valanghe

Tetons

Bridger-Teton Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Sat
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Human triggered avalanches will be very likely at the upper elevations by early afternoon today. Natural avalanches will be possible at the middle and upper elevations as well. While most of these avalanches will just involve the recent storm snow there remains the possibility to trigger a very large avalanche in isolated areas. The slopes with unsupported terrain features on the southern half of the compass are the most suspect but overall very dangerous avalanche conditions exist.  

Problemi valanghivi

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–3

    A weak basal structure highlighted by the November 27 crust/facet layer is present on previously wind scoured aspects. This layer is 20 to 60 cm above the ground and 50 to 100 cm down from the surface in areas that correspond to the highest likelihood of human triggering. While finding the weak spot is unlikely, the resulting avalanche will be very large.

    Todays storm will increase the number of possible triggers through sloughing, cornice failure, rapid loading, and other smaller avalanches. 

    The only way to rule out this problem is by digging a hole in or near the slope you plan to ski or ride. 

    (1/16/2023) Slide initiated on skiers far upper left side of crown in shallower snow and propagated into deeper snow.

  • Wind Slabs

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

    Up to 20 inches of new storm snow is possible by early this evening, with westerly winds in the 25-35 mph range (gusts in the 40s). This will build wind slabs that could be 2-4 feet thick and sensitive to human triggering. This snow lies on a variety of old snow surfaces including, but not limited to, sun crusts, windboard, laid down surface hoar, and possibly small near surface facets. A poorly defined frontal passage is on deck for this afternoon/evening which should signal a peak in natural avalanche activity.  

    Monitor the wind direction and look for evidence of cracking within wind drifted snow. 

  • Storm Slabs

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

    Storm snow totals are forecasted to reach 15-20 inches at the middle and upper elevations by 5 pm this evening, with snowfall rates throughout the day in the 1-3 inch/hour range. This snow lies on a variety of old snow surfaces, including - but not limited to - sun crusts, windboard, laid down surface hoar, and possibly small near surface facets. A poorly defined frontal passage is on deck for this afternoon/evening which should signal a peak in natural avalanche activity.

    Dry loose snow avalanches could become a real concern in steep terrain if the weather forecast validates. 

Avalanche Discussion

Today will bring an interesting confluence of avalanche problems. The Tetons are currently in the midst of a 48 hour long loading period that is being provided by a moist NW flow. Weather highlights include snowfall rates in the 1-3 inch per hour range and possible storm water totals in excess of 2 inches by  Saturday evening. Winds will be westerly and moderate to strong at ridgeline. 

This is a welcome reprieve from a relatively dry NNW flow regime that has left the Tetons with a variety of snow surfaces and riding conditions. Recent avalanches have been confined to wind slabs in the alpine and some dry loose activity.  

Current snow depths range from less than a meter on previously wind scoured aspects to well over 2 meters deep on leeward aspects at the upper elevations. Westerly winds will work to cross load southerly slopes today and build overall slab thicknesses. Significant settlement (and subsequent slab cohesion and tensile strength) should occur over the next 48 hours or so.  

 

 

 

 

Regioni coperte