Avalanche forecast

Presidential Range

Mount Washington Avalanche Center
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Avalanche danger

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

Today the upper and middle elevation slopes will be prone to large avalanches due to wind drifted snow on eastern aspects. Both new and older slabs will be capable of avalanching naturally or triggered by human influence. There is a potential for surface avalanches to step deeper into older and still reactive slabs formed in the past few days.

Avalanche problems

  • Wind Slabs

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

    Wind drifted slabs will continue to grow and become more sensitive today as new and blowing snow is cast onto east facing slopes. Yesterday's slabs were +1Finger in hardness and up to 2 feet thick in some locations; from the 6 inches received Tuesday night. Last night another 5 to 7 inches of new snow fell with moderate west winds. Today, expect winds from the northwest to increase throughout the day, likely breaking the 100mph mark later this afternoon. 

    This wind loading scenario means that areas where avalanches occurred yesterday will have refilled with transported snow and remain an issue to travelers throughout today. Continuous loading and snowfall overnight will have built new slabs upon the previous ones compounding the volume of potential avalanches. There is an increased likelihood of step-down avalanches occurring that could be nearly 4 feet in depth. 

Avalanche Discussion

This morning's snow totals come with a bit of interpretation due to differing measurements across a small area. Harvard Cabins caretaker & Hermit Lake’s automated system reports about +6 inches of snow while Gray Knob measured 2.7 inches and the summit MWObs reports 2 inches. The snow that was recorded overnight was very low density, somewhere around 6%. This means that larger flakes with more surface area and increased pore space make a small amount of snow water equivalent look like a dramatic amount of accumulation.

Yesterday’s avalanches that had occurred overnight in Tuckerman Ravine were apparent during the early morning sunshine, but faded in contrast later in the day. Clouds and blowing snow obscured visibility and the signs of recent avalanche activity. Debris was eventually observed in the run outs of popular ski runs such as: Hillman’s, Chute, Left Gully, Lip, and Upper Headwall. These natural avalanches were large enough to bury a person.

The wind loading of slopes on Mount Washington is so consistent that it can be easy to become complacent when the same avalanche problem occurs day after day. Today is not the day to be in this mindset. Use the indicators of blowing snow banners at ridgelines, firm surface slabs with soft snow underneath, and today’s Considerable hazard rating as reason to adjust your plans.

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