Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

Thu
Alta quota
1 · Debole
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

You may be able to trigger a small avalanche today in east-facing terrain that is protected from the wind between 3,000-5,000 feet. Look out for bright white smooth snow to identify areas that could be unstable. Traveling on the icy, refrozen surface limits your exposure to potential avalanches, but necessitates the use of mountaineering equipment and the skills to use them.

Problemi valanghivi

  • Wind Slabs

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

    What and where is it: The Mount Washington Observatory has recorded over 3 inches of snow from 12/29, once temperatures dropped below freezing. Winds have been predominantly out of the west, with 21 hours of wind speeds over 90 mph. In sheltered east-facing terrain, which includes Summer Lion Head Traverse, you may find areas with smooth drifted snow that is capable of producing a small avalanche.How can you recognize it: The predominant surface you will encounter will be a slick, melt-freeze crust from rain and warm temperatures on 12/29. This will easily be identifiable as a grey old snow surface. In contrast with this will be new snow drifts, which will appear bright white and smooth.

    How can you manage it: Visually inspect terrain to plan your route as you travel on steep eastern slopes. Look for sheltered terrain that has smooth white snow as potential areas of concern. Travel around them to reduce your exposure to an avalanche today. If you choose to travel through a new drift, dig down to the snow interface to assess sensitivity with hand shears and column tests. Persistent cold temperatures may weaken this interface over time. While the size is expected to be small, a small avalanche could lead to a fall that is impossible to stop, and could be hazardous if it leads to exposed rocks, trees, or cliffs. 

Avalanche Discussion

Historically, after this many hours of extreme winds, it is hard to find evidence of soft snow or an avalanche problem. It is entirely possible that this may be what you find today in steep snow-covered slopes. 

A forecaster found deep reactive drifts and talked to a group that crossed the Summer Lion Head Traverse and found deep drifts and cracking snow. This may only be what you find in extremely sheltered features, which could also include areas like under the ice bulge in the Gulf of Slides in Main Gully. If this is the case, the avalanche hazard may be lower due to the limited distribution of the avalanche problem. The Summer Lion Head Traverse is highly sheltered terrain that can harbour a small wind slab in extreme wind events. A small avalanche there is extremely consequential due to the exposure over rocks, trees, and cliffs.

Due to lack of field observations (likely due to the extreme cold and wind yesterday), there is limited data on the majority of avalanche paths. While there is a fair amount of uncertainty today around the listed wind slab problem, your travel remains relatively simple. Traveling on firm icy surfaces will reduce your exposure to any avalanche hazard, but it does have the risk of contributing to a fall that may be difficult to stop. Sure-footedness with crampons will be your best tool against a fall, but it will be a good day to carry an ice axe as well. Assess areas of smooth snow before committing to traveling across them, and consider submitting an observation of what you find!

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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