Avalanche Advisory for Saturday, December 17, 2016

This avalanche advisory expires at Midnight tonight.

Huntington Ravine has HIGH and CONSIDERABLE avalanche danger. Central, Pinnacle, Odell and South Gully have High avalanche danger. Natural avalanches are likely and human-triggered avalanches are very likely. North, Damnation, Yale, and Escape Hatch have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely.

 Tuckerman Ravine has HIGH and CONSIDERABLE avalanche danger. Sluice, The Lip, Center Bowl, Chute, Left Gully and Hillmans Highway have High avalanche danger. Natural avalanches are likely and human-triggered avalanches are very likely. Lobster Claw and Right Gully have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Lower Snowfields and Little Headwall are not rated due to a lack of snow though a portion of the Lower Snowfields could be struck by avalanche debris from Duchess.

Very dangerous avalanche conditions will exist in both Ravines today.

AVALANCHE PROBLEM: 4-8” of new snow on increasing winds will build dangerous wind slabs today. Wind loading will form cohesive, unstable slabs of snow on top of softer, cold dry snow deposited by diminishing winds yesterday. Many avalanches paths ran in the past 36 hours and then reloaded so anticipate larger avalanches in some locations that will run further onto the floor than you might expect. The floor of Tuckerman Ravine would not be a good place to travel today. Several “red flags” exist today that will challenge even the most advanced avalanche practitioner so think hard if you want to try to outsmart the avalanche problem.

WEATHER: Winds currently from the southwest in the relatively light 35 mph range will increase and shift west this afternoon. This shift and increase in velocity to the 40-55 mph range will mark the transition to our peak natural avalanche potential. Gusts reaching 65 mph may transport enough snow today prior to the main shift in speed and direction. We are starting the day at 0F on the summit though temperatures will reach 20F or so by dark.

SNOWPACK: Clear visibility yesterday afternoon gave us a brief opportunity to observe signs of widespread avalanche activity in both Ravines. Yesterday’s avalanches appeared to be small to medium sized (R1-3) but I doubt that will be the case later today and tonight if the precipitation and wind forecast plays out. Our slopes and gullies have grown quite a bit since the start of the month, with avalanche debris stretching further down into the avalanche paths after each cycle. We have had very cold temperatures over the past few days which has not helped with snow settlement and may have even driven a faceting process near the deep ice crust that exists in some shady aspects. If venturing into the terrain today, know that poor visibility due to fog and blowing snow will challenge assessment and safe travel techniques. Upper start zones may be very different than the snow that you are traveling on below. For this reason, I would stay out of the path of any open slope or gully. A complex snowpack and multiple red flags will make it a good day to avoid avalanche terrain altogether.

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 so you can avoid the detour. Please be careful of construction debris near crossover 7 on the Sherburne Ski Trail. Thanks for your continued patience!

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 8:05 a.m., Saturday, December 17, 2016. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2716

2016-12-17