Bollettino valanghe

Tetons

Bridger-Teton Avalanche Center
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Pericolo valanghe

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

In sintesi

Recent snow yesterday and last night combined with increased wind speed out of the northeast will create unstable snow on specific slopes in the upper elevations. Look for obvious signs of wind loaded slopes such as cracking, stiffened surfaces, and large pillows/drifts. These wind slabs will be most reactive on slopes where recent snow fell on a fairly widespread crust.

Problemi valanghivi

  • Wind Slabs

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

    Wind slab development was minimal yesterday, but shifting wind with increased speed last night will form slabs up to 1-2 feet deep in upper elevations. Wind speed increased last night to above 30 mph at JHMR Summit (10,450’) since 22:00, shifting out of the northeast. Wind slabs will likely not be widespread, and be found on isolated-specific terrain. Look for those obvious signs of wind loaded slopes off ridgelines, convex rollovers, below cliffs, and confined features such as couloirs. NE wind is atypical for this area, so look for wind slabs formed in unusual areas today, especially on W-S-E aspects under a fairly widespread crust.

    Cracking snow surfaces provide an obvious sign of instability on wind loaded terrain. 

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–3

    Weak snow formed in December is persisting 3-5+ feet deep below hard slabs.The early March storm cycle produced very large avalanches on these weak layers, with the last reported avalanche on 3/5. These occurred on heavily wind loaded terrain and below cornices. The impact of a rider triggering these layers is unlikely. Still the primary terrain that is most hazardous includes very steep, unsupported slopes above cliffs and rocky or notably shallow slopes. Thin spots in the snowpack are more likely to act as trigger points in these locations. Keep in mind that a cornice fall will make it possible to trigger one of these very large avalanches. As always, give cornices a wide margin of safety as they can break further back than expected. 

    (3/5/2024)

    Very large persistent slab avalanche that failed during the early March storm cycle. This terrain characterizes where this problem is most relevant. Very steep, unsupported slopes above cliffs. Also note the large cornices and potential trigger. 

Avalanche Discussion

Prior to this overforecasted storm the last two days, warm temperatures and solar influence formed crusts on W-S-E aspects up to 10,000'. Recent snow will be most unstable on these aspects, especially on wind loaded leeward slopes from NE wind. Weather stations have reported 4-6” over the last two days. Some areas received a lot of graupel, which will transport easily with wind. Wind speed is forecasted to taper off throughout the day, so monitor active wind loading during your travels. Wind slabs will be most reactive in the higher areas of the upper elevations in open, exposed terrain. Wind slabs will be confined to very isolated terrain in the middle elevations. Watch for dry loose activity and sloughing of new snow in the middle to upper elevations, especially above 8500'.  Natural dry loose was observed and slough management was necessary in GTNP yesterday on steep slopes. These can knock a rider off their feet in steep terrain. Pay attention to solar influence in the afternoon on southerly aspects destabilizing recent snow. Low danger does not mean no danger. Assess recent snow instability across all elevations. 

Over the next several days we will enter a drier warming trend. With the arrival of spring, folks will be getting out the door earlier in the morning for alpine starts when forecasts are not published yet. In these cases, remember to do your research on changing weather conditions before entering the mountains. Slight changes in wind direction and speed will significantly help inform your travel plans and objectives. Remember to assess new snow instability yourself and continue to submit observations to improve information sharing for the community. Thank you and enjoy the fresh snow today.

Regioni coperte