Avalanche Advisory for Tuesday, April 5, 2016

This advisory expires at 12:00 midnight.

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche  danger. Right Gully and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. All other forecast areas of Tuckerman Ravine have CONSIDERABLE avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential. Lobster Claw, Lower Snowfields and Little Headwall are not posted due to lack of snow.

Huntington Ravine is under a General Bulletin. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Today’s avalanche problem is Wind Slab. Wind slab and avalanche danger will build throughout the day as winds increase. This wind slab will develop on very light density snow and is likely to be touchy even in Moderate rated areas. As the day progresses and loading continues, the likelihood of a naturally occurring avalanche and the potential size of an avalanche will increase, particularly in Considerable rated areas. Entering the floor of the ravine today will potentially put you in the path of avalanches.

WEATHER: Temperatures 15-20F below normal the past several days brought wintry conditions back to the mountain. The summit recorded 8″ (20cm) of snow over the past three days with 4.7″ (12cm) of that total yesterday. Hermit Lake received 6” (15.5cm) yesterday. Winds somewhat dampened yesterday as well as shifted to NNW, and now out of NW. High pressure will sweep in today, allowing skies to clear. Temperatures will remain cold and winds will increase to 50mph+ (80kph) by the end of the day.

SNOWPACK: Small accumulations of snow each of the past three days have allowed wind slabs to gradually increase in size. Throughout the day yesterday, very light 3% density snow fell on W shifting NW winds of 20-35mph. With winds increasing through the day today to ideal loading direction and speed, new wind slab will form and grow in size and thickness with an upside down configuration due to increasing winds. These slabs will be touchy to human triggers and may naturally release by this afternoon. While wind slab formed on Sunday will be stubborn to trigger by a human, it is possible for an avalanche in the newly formed wind slab to step-down into this older layer, dramatically increasing consequences. Traveling in avalanche terrain today will require careful snowpack evaluation.

The same winds that loaded our terrain with snow have also scoured several areas, leaving the old rain crust visible. Arresting a fall on this hard layer of icy snow will be next to impossible. Long sliding falls can be disastrous, particularly if they take place above a rocky run out or an open crevasse.

The Sherburne Ski Trail is now closed at #7, allowing about 2/3 mile of skiing from Hermit Lake. Expect exposed ice with new snow. The Harvard Cabin is closed for the season. The only camping permitted in the Cutler Drainage will be at Hermit Lake Shelters.

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 8:45 a.m., Tuesday, April 5, 2016. A new advisory will be issued tomorrow.

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

2016-04-05