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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The chance for an unpredictable large, wet avalanche remains a possibility until the snowpack drains and refreezes. Once rain changes to snow, watch for wind drifted snow capable of sliding on easterly aspects above 2000 feet. A long sliding fall hazard will develop on steep terrain requiring the use of crampons and careful movement.

Avalanche problems

  • Wet Slabs

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

    Steady rain this morning keeps this avalanche problem in the forecast. Likelihood of wet slab avalanches will decrease as temperatures fall, though remain a possibility until the snowpack fully drains of free water and refreezes. Wet slab avalanches are challenging to predict, and lack subtle red flags except for the obvious rain and melting snow. Respect avalanche terrain for the next 8 hours for this low probability high consequence event.

    NWS hourly forecast for Mt. Washington. 7am 2/18/2022

  • Wind Slabs

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

    Rain will turn back to snow this morning with 1-3 inches possible. Strong wind from the northwest will transport new snow from the west side of the range onto easterly aspects creating wind slabs up to 1.5 feet thick. Fresh slabs may be reactive to a human trigger, especially when found in wind protected areas. With temperatures dropping through the day, new snow will start warm and end cold, likely adhering well to the existing surface as it re-freezes. You can easily check for this by using simple hand-shear tests along the way in your travels. Watch for shooting cracks in the new snow as a red flag for instability. 

Avalanche Discussion

The Considerable hazard rating this morning reflects the possibility of a large, wet natural avalanche. Rain and meltwater is the primary driver for instability though the first half of the day. As of 5am the summit of Mt. Washington has received 0.28 inches of rain in the previous 24 hour period, and Hermit Lake has lost almost 6 inches of snow due to settlement and melting. Up to 0.25 inches of additional rain may fall early this morning before precipitation ends or turns back to snow. As temperatures drop this hazard should decrease, though keep in mind the snowpack is a thermal mass and will take some time to fully refreeze

The headwall Lip area of Tuckerman Ravine is one area that has occasionally seen dangerous wet slab avalanches from the river of meltwater below. In 2018, 2+ inches of rain produced a wet avalanche 160’ wide which ran 2000’ onto the floor of the ravine. See this post for more details. 

Keep wind slabs on your radar for the afternoon. With warm temperatures becoming cold, new slabs should stick well to the existing bed surface and be “right side up”. Deeper slabs will be a concern as they may fail within the new snow. Look for density changes as strong wind loads and cross loads in eastern ravines. 

Lastly, steep slopes will refreeze hard, and may be smooth if wind scoured off any new snow. Be mindful of long sliding falls, realizing that even a small avalanche may initiate a fall in steep terrain. 

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

Please help us and your fellow skiers, riders, and climbers by submitting any pertinent or interesting observations to our website. 

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