Avalanche Advisory for Monday, December 19, 2016

This advisory expires at Midnight tonight.

All forecast areas in Huntington and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Around half an inch of rain yesterday has effectively reduced our avalanche problem to Low. If it wasn’t for the possibility of encountering some small wind slabs behind wind breaks, beneath steep features and cross-loaded in steep gullies, there would be no avalanche problem at all. Trace amounts of snow fell since our rain event have built these slabs. Even small avalanches can create problems on our icy bed surface. These should be easy to identify contrasted to the old darker, refrozen snow surface. Otherwise, your larger travel concerns today will be a wide variety of refrozen snow and icy surfaces.

WEATHER: After reaching a high temperature of 40F (4C) on the summit yesterday, we have returned to near seasonable temperatures this morning after a visit with -11F (-24C) last night. Some scattered clouds remain overhead but otherwise clear visibility and cold temperatures around 0F mark the start to the day. As high pressure continues to settle in, expect winds to slacken even further and shift west into the 25-40 mph (40-65 kph) range. Temperatures on the summit will continue to rise until they reach into the mid-single digits today and mid-teens tomorrow.

SNOWPACK: Time to put your skis away for bit and enjoy favorable ice climbing and mountaineering conditions. The nice dump of new snow that came on Saturday along with the rest on the above average December snowfall has been soaked and refrozen into a variably breakable ice crust. While you could pretty easily move around in most terrain last week without crampons, that is not the case today. Along with this refrozen surface comes the risk of long sliding falls on steep terrain so move carefully since self-arrest probably won’t work on a steep slope in these conditions. A breakable crust in the woods and on flatter terrain that wasn’t previously wind packed or scoured is likely to be breakable and at higher elevations that could be a real problem if you find yourself off-trail or on seldom traveled trails. Wallowing in deep snow beneath a breakable ice crust that scrapes the skin off your shins is no way to spend the day. As mentioned in the avalanche problem discussion, you’ll find some pockets of new wind slab.

The Lion Head Winter Route is open and the most direct route to the summit from the east side of the mountain. While not technically closed by law or Forest regulation, the Lion Head summer trail above Hermit Lake is threatened by several avalanche paths, making the Winter Route a better option when avalanche conditions exist. 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 Trail and some snow machine and snow tractor traffic as some final work for the season continues. 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 7:45 a.m., Monday, December 19, 2016. A new advisory will be issued tomorrow.

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