Avalanche forecast

Presidential Range

Mount Washington Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low
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Highlights

Dangerous avalanche conditions exist today on east-facing and south-facing slopes. Areas of thick wind-drifted snow have the ability to create large avalanches that could happen naturally or by the weight of a person. Cautious route-finding and informed, conservative decision-making is critical when traveling in or near avalanche terrain today.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Thick wind slabs sensitive to human triggers will continue to form throughout today and tonight at middle and upper elevations on east-facing and south-facing slopes. Steadily increasing wind speeds over the past 24 hours have formed strong-over-weak slabs that could be several feet thick. As more time exposed to high winds passes, these slabs may become increasingly stubborn to trigger from the weight of a person. The likelihood of finding a thin spot (like a buried rock) with this avalanche problem is increased due to the early season snowpack and could be the trigger-point for a large avalanche. 

    This problem can be identified by observing red flags including wind-transported snow at the ridgelines, recent avalanche activity, whumping sounds, and long, shooting cracks underfoot.

Avalanche Discussion

The forecasting team still recognizes the uncertainty of size, distribution, and sensitivity of these new wind slabs. With little visibility during the day yesterday and significant amounts of risk associated with approaching avalanche terrain, the data is still limited.

The significant snow storm over the weekend brought big snow totals of up to 30” in some areas in the Presidential Range forecast area. Yesterday, wind speeds took longer than expected to increase and resulted in less wind-loading during the daylight hours. As winds ramped up into the 50 - 60 mph range overnight, it is likely that a period of heavy wind-loading occurred overnight with the potential to have built large wind slabs moving into today. 

Wind slabs in lee areas are likely many feet thick and could be reactive to human or natural triggers, especially if a thin spot is found where a weak layer can translate a collapse across a larger slope. Even as new slabs begin to gain strength and start to become less sensitive over the next hours and days, this will remain a concern for skiers and climbers. Thin spots can live under smooth and planar snow surfaces, making them difficult or impossible to identify from a distance. The amount of exposed rock and ice before the recent storm are an indication that thin spots are plentiful this time of the year. 

With an early season snowpack, the consequences of being caught in even a small avalanche today are severe. Exposed rock, water ice, and vegetation exist in almost every avalanche runout zone and greatly increase the risk of traveling in avalanche terrain today.

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.

Regions covered