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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Out of date — this forecast expired 7 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

You could trigger a small avalanche as new wind-drifted snow accumulates in east-facing terrain above 3000 ft. While less likely today, avalanches could also break deeper in the snowpack. Look for blowing snow and shooting cracks as signs of today’s developing surface problem. Travelling on scoured old snow surfaces reduces your exposure, but still requires snowpack assessment for buried weak layers. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    What and where is it: New small wind slabs will form throughout the day from 1-3 inches of low-density snow. Extreme west winds will likely limit the size of developing wind slabs.

    How can you recognize it:  Active blowing snow and plumes of snow blowing at the ridgelines are signs that wind slabs are forming; slabs will be most reactive at this time. Pay attention to snow drifts accumulating and dig down to assess the interface with the old firm snow surface. Shooting cracks and drifts deeper than your boot tops are signs of new wind slabs.

    How can you manage it: Visually assess terrain before you commit to traveling through it. Look for active loading or recently formed wind slabs that will be bright white. Traveling on textured old snow surfaces will limit your exposure to new wind slabs, but you still could be on a buried persistent slab on top of a slick melt-freeze crust that could produce a large and destructive avalanche. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–2.5

    What and where is it: Old, hard slabs are sitting on top of weak snow on top of a slick melt-freeze crust formed on January 10th between 3000 and 5000 feet in elevation on easterly aspects. 

    How can you recognize it: This avalanche problem won’t be identifiable from the snow surface. Probe to identify if the structure of a weak layer and a crust is present; you should be able to feel these hardness changes. If you find this structure, consider digging deeper into the snowpack and use tests like an extended column test (ECT) and propagation saw test (PST) to assess the propensity for propagation. 

    How can you manage it:  Understanding where this problem exists is the best way to manage this problem. The most likely scenario of you triggering this layer would be triggering a surface slab that steps down to the buried old slab, which could increase the destructive potential of a wind slab avalanche.

Avalanche Discussion

Active weather patterns continue so active decision-making today should be part of your tour plan. Over an inch of snow has been recorded so far, with around 2 inches forecast to fall in the late afternoon. The combination of low-density snow and extreme winds is not likely to create large wind slabs, but expect to assess newly forming slabs throughout the day.

Today’s decrease in avalanche hazard is a combination of yesterday’s observations and the low-density precipitation forecast today. However, there are concerns and weak layers in the snowpack beyond the surface.

The persistent slab is formed from the 1/10 melt-freeze crust and then old wind slabs that have been loaded on top of it. Because the original problem was a wind slab, the distribution and size are highly spatially variable. In most east-facing terrain, this crust is still less than 3 feet from the surface, meaning that it is something that you could trigger, so it remains a concern and a forecasted problem. 

However, in some east-facing terrain, this crust is exposed to the surface, and in other places, it is only shallowly buried. While it may not be a present concern everywhere, it is a layer that exists, should be assessed, and be a part of all terrain considerations. It is also a layer that still may be subtly changing, with weak layers becoming weaker as continued cold temperatures cause snow metamorphosis and faceting. This problem requires more time to understand than just a surface avalanche problem, and is more challenging as it will provide less reliable feedback. 

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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