Avalanche Advisory for Tuesday, December 13, 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: Today’s avalanche problem will be Wind Slab created from yesterday’s storm and from today’s winds. Snowfields are rapidly growing past early-season size. In places, some forecast areas are becoming connected with others. Small avalanches are possible in many locations and the potential for large avalanches now exist in a few locations, particularly the area from the Chute over to the Lip. Runouts are filling in, but still contain a number of boulders and broken cliff bands that create further hazards. Cautious route-finding today should be at the front of your mind.

WEATHER: The summit of Mount Washington received 9.3″ of 9% snow yesterday. The bulk of the snow fell on light to moderate south winds that wrapped around to the west as the day progressed. As the wind shifted, wind speed increased through the prime snow transporting speeds, gusting to the mid-80mph range in the overnight hours. We may see periods of clearing skies today, but I would expect the steady W/NW winds to cause whiteout conditions for the majority of the day. A trace of new snow is called for today with up to another 2″ overnight. 

SNOWPACK: Before yesterday’s snowfall, our snowpack consisted of layers of windslab mixed with layers of graupel, all sitting on top of a melt-freeze crust. Natural avalanche activity prior to yesterday in several locations proved that these layers were reactive when loaded. The 9″ that fell yesterday arrived on shifting and increasing windspeeds. There was also a period around noon and again late in the evening where we saw heavily rimed snow falling. A natural avalanche was witnessed out of Dodge’s Drop yesterday morning. These factors, combined with other red flags, are all pointing to multiple unstable layers. Visibility is minimal this morning, but I would guess several forecast areas have seen at least one avalanche cycle and are loading up for a second if not already a third. Avalanches stepping down into the windslabs developed over the past week may be a possibility. Entering the floor of either ravine today puts you in avalanche terrain with multiple paths above. Dangerous avalanche conditions exist today. Conservative decision-making will be paramount.

The Lion Head Summer Trail remains the better route to the summit. We are keeping tabs on the development of the avalanche paths that threaten that trail and will switch to the using the winter route as snow continues to fill in things. 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 so be on the lookout for them and for machinery 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 8:10 a.m., Tuesday, December 13, 2016. A new advisory will be issued tomorrow.

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

2016-12-13