Avalanche Advisory for Saturday, December 31, 2016

This advisory expires at Midnight tonight.

All forecast areas in Huntington Ravine have MODERATE avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully.

 Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. Sluice, Lip, Center Bowl, Chute and Hillman’s Highway have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Lobster Claw, Right Gully and Left Gully have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully. Lower Snowfields and Little Headwall are not rated due to a lack of snow but look for overhead hazard in Lower Snowfields which is remains tree covered except beneath Duchess.

AVALANCHE PROBLEM: Large, smooth but stiff and probably stubborn wind slabs exist throughout our Considerable rated terrain remain in the wake of the 24” of snow that fell in the past 36 hours. Our Considerable danger ratings are more likely straddling the line with a Moderate danger rating due to a somewhat reduced likelihood of natural avalanches. In Huntington, our danger rating of Moderate is edging towards Considerable in many areas like in Central, the approach and second pitch to Pinnacle, and low on approaches to northern gullies. It is worth remembering that remaining wind slabs may be sitting in top of an icy crust and probably not all that well bonded. Protect yourself with safe travel techniques and evaluate suspect snow and terrain features. Softer and more sensitive wind slabs are also something to look for and avoid. Steep but more protected terrain may hold sensitive pockets more easily triggered by a person.

WEATHER: The temperature on the summit is -8F with wind from the west around 60 mph. Wind transported snow continues to blow into our terrain, particularly in Tuckerman Ravine. Wind will shift to the SW today and decrease to 35-50 mph which will effectively stop wind transport of snow. Air temperature will rise to 10F on the summit. Visibility is already diminishing due to fog. Expect clouds to descend on the summit by nightfall as another round of precipitation begins, potentially bringing 3-6” more snow overnight.

SNOWPACK: While no crown lines exist to tell the tale of the avalanche cycle that occurred yesterday, it is only because of the continued loading of new and wind transported snow covered them all up. Debris is obvious and extended well out into the floor of Tuckerman Ravine and ran 200m beyond previous avalanches this season. The debris is very deep and ran across the trail and into the woods ending about 100 yards above the Connection Cache. This is a powerful reminder that you are well into avalanche terrain if you go beyond the Cache to “look around”. In Huntington, avalanche debris remains visible well below Central Gully and clearly rounded the corner in Hillman’s Highway. The ice crust remains a player in our stability picture even though it is buried most everywhere in our forecast area. Crusts serve not only as a slick bed surface, but also as a layer to develop weak, sugary facets just above and below.

The Lion Head Winter Route is open and the most direct route to the summit. The Tuckerman Ravine Trail bridge is completed enough to allow traffic again. Please be careful of construction debris near crossover 7 on the Sherburne Trail when skiing or riding.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
  • Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
  • For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted 8:25 a.m., Saturday, December 31, 2016. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2016-12-31