Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
3 · Marcato
Sotto il limite
1 · Debole
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In sintesi

You could trigger a large, destructive avalanche on north, east, and south aspects above 3000 feet. Traveling strategically and making conservative terrain decisions while carefully assessing the snowpack will be critical for safe travel in avalanche terrain today. The snowpack may give limited warning signs of a dangerous, large, and hard slab avalanche. 

Problemi valanghivi

  • Wind Slabs

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

    What and where is it:Large, potentially destructive wind slabs have formed from about 30 inches of new snow and high winds over the past week. Expect to find large wind slabs across north, east, and south aspects. Above 3000 feet, slabs may be deeper, softer, and more sensitive to your weight. Above 5000 feet, slabs are likely to be firmer and more difficult to trigger.

    How can you recognize it: Look for smooth, rounded snow slopes in wind-protected areas where the wind has worked to build large wind slabs. Shooting cracks under your feet, hollow-sounding snow, and deep drifts of softer snow are signs of a wind slab avalanche, but it is possible to be traveling on a harder, dangerous wind slab without obvious warning signs. 

    How can you manage it:Travel strategically in avalanche terrain and work to reduce your exposure and time spent underneath large, connected snow slopes where dangerous wind slabs could be sitting above you. If you are uncertain about the sensitivity or location of the avalanche problem, consider an alternate route.

  • Persistent Slabs

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

    What and where is it:Old hard slabs are sitting on a buried persistent grain layer and continue to show the potential for instability above an ice crust bed surface. Forecasters have identified this structure as having the potential to slide on east and south aspects above 4000 feet. This faceted structure has been found in the snowpack, with specific areas like the Summit Snowfields and gully entrances on the south face of Tuckerman Ravine having sensitivity in snowpack instability tests. Additionally, on February 4th a very large avalanche on the Gulf on Slides Southern Snowfields stepped down to this layer and the possibility of this happening elsewhere remains. Note that one of the places this avalanche problem exists is just to the north of where the Lion Head Trail leads to Split Rock on the summit cone and on the Summer Lion Head Trail.

    How can you recognize it: Identifying this avalanche problem is difficult without digging a deep pit, as there will be no visible clues. "Whumping" sounds as a warning are unlikely, and the slopes will likely appear unreactive. How can you manage it:Understanding where this problem exists in the terrain is the best way to minimize your exposure to the hazard. Plan your travel to avoid these isolated areas of a low-probability but high-consequence avalanche problem.

Avalanche Discussion

Triggering a high-consequence avalanche is possible today. In many areas, it is likely that new wind slabs and older persistent slabs have become increasingly stubborn to trigger, however, the consequence remains high. Because of this, effective terrain management is absolutely critical if you choose to travel in avalanche terrain today. Reducing time spent in an avalanche path, minimizing your exposure to avalanche problems overhead, and traveling one at a time are a few ways to reduce your risk. There is some amount of uncertainty around how effectively the high winds yesterday stabilized the snowpack on leeward (wind-protected) aspects. The wind may have had a stabilizing effect on some slopes, but this is impossible to know for sure without some snowpack investigation. Remember to choose representative slopes that don’t expose you to the avalanche hazard if you choose to investigate the size and sensitivity of today’s avalanche problems. 

OBSERVATIONS: Please consider submitting an observation on our website or in the new Avy phone app of what you are seeing in your travels. Submitting an observation hones your skills, informs other users, and improves our forecasts.

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