Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

Fri
Alta quota
1 · Debole
Limite del bosco
2 · Moderato
Sotto il limite
Senza grado
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In sintesi

You are most likely to trigger an avalanche on steep east and south-facing slopes above 3000 feet today. Look out for areas of smooth drifted snow that could be found below ridgeline, cliffs, or in narrow gullies. Traveling on firm, textured snow surfaces will limit your exposure as will choosing lower-angle terrain or terrain with fewer consequences.

Problemi valanghivi

  • Wind Slabs

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

    What and where is it:

    West and northwest wind moved snow onto steep east and south-facing aspects, likely building wind slabs. While natural avalanches are unlikely, it remains possible for you to trigger an avalanche today.

    How can you recognize it: 

    Look for smooth, drifted snow to identify today’s problem. This bright white snow will be in contrast to textured snow surfaces around it. Blowing snow at ridgelines, cracking under your feet, or softer snow that is deeper than the top of your boot, are all warning signs of the avalanche problem.

    How can you manage it:

    With high winds, the sensitivity is likely becoming more and more stubborn, but treat wind-drifted snow guilty until proven otherwise. Traveling on wind-scoured surfaces or wind-textured areas will reduce your chances of triggering an avalanche. Convex features are areas to consider avoiding as these can be stress points on the snowpack. Visual identification will be your best tool, but as you move through terrain, using hand shears or and column tests can help you to understand the sensitivity of the snow. Using a ski pole to probe or your boot penetration also can help you assess the size.

Avalanche Discussion

Forecasters in Tuckerman Ravine yesterday did not observe evidence of wind transport from southwest winds, while it is possible these winds were productive elsewhere. This means that avalanche problems in north-facing terrain are likely to be smaller. Snow transport became more active when winds shifted west, and later northwest, and ramped, making east-facing and south-facing aspects areas where you will be most likely to find today’s avalanche problem. While larger avalanches may be more isolated, you may find them in south and east-facing terrain in areas like Tuckerman Ravine where terrain is highly connected.

One of the questions we are grappling with is the impact of the ramping wind on avalanche size.  Part of our uncertainty comes from just how much snow was available for transport. Today we specifically will be looking for how representative this sizing is. The high winds may have scoured more than loaded, which will result in smaller wind slabs. Areas that may harbor a more sensitive wind slab will be in sheltered terrain, like Summer Lion’s Head Traverse or Gulf of Slides. 

Upper elevations were forecast at low because the wind slab problem is expected to be smaller in that terrain. Upper elevations experience higher wind speeds than the ravines below which are more sheltered. Wind slabs at upper elevations are likely to be smaller and more stubborn than the wind slabs found below 5000 feet.

With continued high winds, you are likely to find stability increasing, but when that exact moment comes is hard to say. Assessment will still be important today as you move on steep slopes with drifted snow. It is worth considering how the extremely cold temperatures forecast today increase your exposure, and it may be worth increasing your margins accordingly.  

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. 

LEDGE BREWING SPEAKER SERIES: Join the Mount Washington Avalanche Center this Thursday, January 30th from 6-8 pm at Ledge Brewing for the first of a monthly speaker series that will explore weather, rescues, forecasts, and more. Tonight, MWAC Director, Jeff Fongemie,  will kick off the series with "Anatomy of a Great Gulf Rescue: A Case Study".  Admission is free, but register 

here.

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