Avalanche Advisory for Friday, December 9, 2016

All forecast areas of Huntington and Tuckerman Ravine have CONSIDERABLE avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Dangerous avalanche conditions will exist today. Cautious route-finding and conservative decision making are essential. Little Headwall and Lower Snowfield are not forecast due to lack of snow.

AVALANCHE PROBLEM: Strong winds are forming new wind slabs in many areas of our terrain today. In most areas these wind slabs will be particularly sensitive to human triggers. Expect some of the forecast areas with more advanced, larger bed surfaces to produce fairly large avalanches which could run into the lower angle terrain. Blowing snow will hamper visibility and make travel into or beneath any avalanche path a sketchy proposition.

WEATHER: Upsloping air rising over the Presidential Range and a cold frontal passage mark the weather today. Temperatures will drop through the day with snow showers producing up to 6” of lower density snow. Forecast wind speeds today (50-70 mph) will be prime for loading the new snow into our terrain. Ultimately the wind could reach into the 90’s mph which will scour out some of the northern gullies in Huntington and harden the wind slabs in Tuckerman. Sustained loading speeds will occur before that so expect peak potential avalanche activity to occur mid-day and into the evening.

SNOWPACK: Almost 2 feet of snow fell on the summit and in our wind fetch zone over the past week. The Bigelow Lawn and Alpine Garden areas, which form our fetch zone, are well filled in, flat, smooth refrozen slush and will not hold the snow in place. Wind will easily transport this snow to create new wind slabs. Initially moderate wind speeds transported this snow into our terrain, first on southwest winds which loaded the lookers left side of Tuckerman and many of the less bushy gullies in Huntington. The snow is surprisingly deep in many areas with climbers earlier in the week in thigh deep snow in pooled areas, mid-calf in others. The snow had a thin, sensitive wind skin with unreactive graupel layers scattered through the terrain last weekend with little opportunities to stabilize much through the week as several passing weather systems have generated light snowfall. I would expect the thin wind slab or mid-pack graupel layers to serve as the weak layer in a wind slab avalanche today.  Despite the disconnected bed surfaces in areas like the Lip and Center Bowl in Tucks, these avalanches are likely to be large enough to bury a person in the terrain traps that exist or to cause traumatic injuries due to the boulders and cliffs that are yet to be buried.

Remember that the bridge work continues on the Tucks Trail so use the detour on the Huntington Ravine trail. Some folks may opt to skin up the Sherburne trail so be on the lookout for them and for machinery on the ski trail.  Be on the lookout for construction debris at crossover number 7 around a mile down from Hermit Lake. It is marked but high winds and drifting could change that. Be sure to report any avalanche activity or snowpack observations through our observation link under the Resources tab above. Internet connections continue to be challenging so check posted advisories at slatboards.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This bulletin 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, or the AMC at Pinkham Notch or Hermit Lake.
  • Posted 9:15a.m., Friday, December 9, 2016. A new bulletin will be issued when warranted.

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

2016-12-09