Avalanche forecast

Presidential Range

Mount Washington Avalanche Center
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Avalanche danger

Fri
Alpine
1 · Low
Treeline
2 · Moderate
Below
1 · Low
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Highlights

You could trigger a large avalanche in firm, wind drifted snow in steep east and south facing terrain today. Look out for bright white and rounded snow to identify new wind drifts that will be in contrast to the dull and icy old snow surface. To avoid this problem, travel on the hard and icy wind-scoured old snow surface.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Hours of extreme northwest wind will have created large, firm, and likely stubborn wind slabs 1-2 feet in depth in south and east facing terrain at middle elevations. With potential for clearing skies, visually inspecting terrain for the distribution of the new wind slab will be easy today. Wind drifted snow will appear bright white and rounded versus the dull and crusty old snow. If you travel in this new snow, assess the interface with hand shears to understand the sensitivity of these likely stubborn wind slabs. Use your ski pole to feel for varying depths to help to understand the size.

    Traveling on the firm, icy old snow surface avoids this avalanche problem.

    Shooting cracks will be a red flag to be wary of in a stiff, pencil hard wind slab. Take advantage of clearing skies to look to ridgelines to see if additional snow continues to be transported. With decreasing winds through the day, new loading could create more sensitive wind slabs. In low elevations there is the potential that steep gullies were cross loaded and lookout for pockets of wind drifted snow. Warming last week resulted in snowpack loss at lower elevations, so the poorly developed paths will be unlikely to produce large avalanches. But consider the consequences of releasing a small pocket in this terrain with exposed trees and rocks.

Avalanche Discussion

The question we asked today was what scoured and what loaded? 

The summit has recorded over 21 hours where winds exceed 65 mph. These strong and extreme northwest winds will have scoured upper elevations and have compressed and firmed snow in wind sheltered terrain. The winds work to not just move the snow, the process also deforms and breaks snow crystals so that they can pack tightly into a cohesive slab. 

For what loaded, we talked about terrain features that tend to harbor wind slabs after high winds. It is likely that slabs will be pushed lower into the terrain in convex features like rollovers or sheltered features. Evaluate new snow critically today and consider the consequence of finding instabilities within new firm wind slabs.

If you find yourself out overnight, new snow and increasing northwest winds will increase the avalanche hazards and have the opportunity to add and make new wind slabs in lee terrain. Approach wind drifted snow cautiously and if you find yourself in snow that is over your boot top consider an alternate route to minimize your exposure. 

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