Avalanche forecast

Presidential Range

Mount Washington Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The chance of triggering an avalanche will increase throughout the day as new snow accumulates. Wind drifted snow on north through west facing slopes will become deep and capable of burying a person. These same drifts may avalanche naturally without a human trigger as the snow piles up. Seek areas without wind affected snow for the safest skiing.

Avalanche problems

  • Wind Slabs

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

    Expect to find sensitive wind drifted slabs building and cross loading onto west through north aspects that will increase in size throughout the day. With moderate wind speeds, these slabs are likely to be more reactive than we typically find with our common higher wind speeds. In the steepest terrain, it is possible for these slabs to avalanche naturally from their own weight. As the snow piles up, developing slabs could be two to three feet thick in some locations, enough snow to easily bury a person. 

    The red flags of new snow and wind, coupled with how snow is behaving under your feet, will be more useful than stability tests in assessing this avalanche problem. Look for shooting cracks as an indicator of instability, though obvious signs of active wind loading are much more significant. 

    It’s also worth noting that wind is forecast to quickly shift to the northwest after dark, which will transport snow and quickly build slabs on easterly aspects. If you are out after dark, keep this in mind.

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    Accumulating loose snow in wind protected areas is likely to slide from a human trigger or naturally on the steepest slopes. Today’s light dry snow may poorly bond with the current hard refrozen snowpack, just waiting for a human or the weight added snow to set it free. 

    Consider the consequences of a fall in steep terrain if loose snow pulls you off your feet.

    Hard snow surfaces in Tuckerman Ravine. 2/24/22

Avalanche Discussion

We are starting the day with a Low avalanche hazard rating. The forecasting team in the field yesterday found a mostly hard refrozen snow surface everywhere. As new snow falls the avalanche danger level will rise through the day reaching Considerable, based on potentially large wind slabs forming on northwesterly aspects. It’s worth noting that due to recent rain the existing snowpack on those same aspects has receded especially at lower elevations. Consequently, the distribution of large wind slabs capable of producing a larger avalanche may be isolated and limited to a few terrain features still holding a developed snowpack. 

Both avalanche problems today are limited to new snow only. After two warm, rainy spells and a return to cold temperatures a thick crust will almost certainly exclude older snow from directly contributing to avalanche size. 

Bonding of the new dry snow may be an issue today. In most places the existing snow surface is hard with some subtle texture. It may be that water vapor remaining in the snow from rain on the 23rd, will help the new snow bond to the melt-freeze crust. Frequent hand shear tests will be a helpful test to check for bonding of the new snow. 

It’s also worth noting that wind is forecast to quickly shift to the northwest after dark, which will transport snow and quickly build slabs on easterly aspects. If you are out after dark, keep this in mind. Wind loading overnight may lead to a widespread natural avalanche cycle in east-facing ravines Saturday morning. 

Thanks to everyone for taking the time to submit observations of snow and avalanche conditions, both inside and outside our avalanche forecast area. Please keep them coming.

The Lion Head Summer Trail is now closed for the season due to avalanche risk. The Lion Head Winter Route is open.

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