Avalanche forecast

Presidential Range

Mount Washington Avalanche Center
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Avalanche danger

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

A second day of very warm temperatures weakening recent snow makes it possible to trigger an avalanche 1 to 2 feet thick. Small wet loose avalanches starting under your feet in steep terrain can help trigger a larger, more dangerous avalanche. Evaluate the consequences of these difficult to predict wet snow type avalanches in any terrain you choose to enter today.

Avalanche problems

  • Wet Slabs

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

    Warming over the last 24 hours has made wet slabs of the wind slabs that formed over the weekend. Despite temperatures hovering around 50 degrees in Tuckerman Ravine yesterday, dry snow exists beneath the wet surface in many places. Free water from melting snow will continue to infiltrate and weaken bonds within this dry snow, increasing the likelihood of triggering. In some areas, such as Tuckerman Ravine, these slabs can be 1 to 2 feet thick and capable of producing a large avalanche. 

    Wet slab avalanches are characterized by uncertainty, with the timing of peak instability quite difficult to pin down. Exactly when and where you might trigger a wet slab avalanche is very hard to predict, making today a particularly poor day to attempt to outsmart the avalanche problem.

    It’s worth noting that temperatures are driving the decrease in stability and will affect all aspects where wind slabs exist, not just south facing aspects. 

    Traveling on snow no deeper than your boot top is the most effective way to avoid a large wet slab avalanche.

    3/17/22 Rollerballs in Tuckerman Ravine yesterday are a red flag for a warm & wet surface snow. 

  • Loose Wet

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

    Wet loose avalanches are possible on all aspects and all snow surfaces in steep terrain. These wet sluffs will be easy to initiate under your skis or board and carry a lot of weight. They can easily knock you off your feet, so consider the consequences of a sluff-induced fall in terrain you choose. These sluffs may also help trigger a wet slab avalanche by adding a significant amount of mass to a human trigger, penetrating deeper into the snowpack.

    3/17/22 Human triggered wet loose avalanche in Tuckerman Ravine

Avalanche Discussion

Today’s wet slab avalanche problem exists mainly where wind slabs formed last weekend. On Saturday March 12th, 12-14 inches of new snow was subsequently affected by several days of strong wind, leaving us with a mixed bag including scoured surfaces, firm wind slabs and softer pockets of snow. New wind slabs were obvious in steep terrain, with the largest in the direct lee of the northwest wind. 

On Tuesday, we found that the new slabs were bonded well to the old snow surface which is to be expected given the warm temperatures at the start of the 3/12 storm. Within the new snow, density changes were observed near the bed surface which reacted moderately to stability tests. 

On Wednesday, a skier triggered a dry slab avalanche in Left Gully, likely failing on the weaker layers near the old snow.  

Yesterday a D1 wet loose avalanche was triggered in Tuckerman Ravine. 

Also yesterday, it was reported that a party of two climbing Odell Gully in Huntington Ravine were caught and carried by a wet snow avalanche. No one was injured. 

Layers of concern may still exist beneath the wet snow surface, especially where the slabs are the thickest. Warming and melting is certain today. Free water moving through the snowpack is certain today. The uncertainty is when and if water can weaken the slabs enough for the weight of a human, perhaps with added weight of wet loose snow, to trigger an avalanche.   

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

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