Avalanche Advisory for Friday, April 21, 2017

This advisory expires at Midnight.

 

Huntington and Tuckerman Ravines have LOW avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. Generally safe avalanche conditions exist.

AVALANCHE PROBLEM: As precipitation continues today with 1-3” of snow and sleet arriving, skier-induced loose-wet sluffs will need to be managed appropriately. These sluffs may be capable of pulling people to an undesired location, particularly in steeper terrain. Our snowpack has absorbed a lot of water through melt over the past week and seems relatively stable. That being said, with unique hazards like the waterfall hole in the Lip, our snowpack can do unexpected things. At times, this area has become plugged due to collapsing snow or a dislodged ice chunk, sending a large amount of water into the snowpack and released a deep wet slab avalanche.

WEATHER: Low pressure moving across New England will create continuous precipitation today. The current temperature on the Summit is 24F with a SE wind of 34mph and light snow showers. As the wind shifts to the S and increases to 35-50mph, warmer air will arrive from the seacoast, transitioning the snow into mixed precipitation and possibly rain. Precipitation will be heaviest in the morning with up 1-3” of snow and sleet by dark. Tonight, wind will shift to the W, decrease slightly with another possible 1-3” of snow and sleet.

ADDITIONAL HAZARDS:

  • Long sliding falls Crampons are highly recommended in steep terrain. Snowshoes and microspikes are no substitute. Arresting a fall on an icy 30+ degree slope can be practically impossible, even with an ice axe. As the temperature drops this afternoon, the snowpack will lock up and provide a fast sliding surface. Keep in mind what is below you when moving around.
  • Crevasses or glide cracks, moats and waterfall holes – Water flowing under the snow pack creates holes and thin spots in surface that are deep enough to injure or kill you. New snow can drift and obscure the openings. Glide cracks, our version of crevasses, form when the snowpack gradually creeps downhill. As the snow pulls away from a cliff, this creates a gap that could swallow a person. The glide cracks are becoming more widespread and a number of them are now big enough that someone could disappear into one. The waterfall hole in the Lip is growing each day as well as the glide cracks that criss-cross this slope. If ascending or descending this particular route, glacier-travel techniques may be useful.
  • Icefall: This hazard is unpredictable but above freezing temperatures certainly increase the risk of ice releasing from a cliff. Ice will fall, roll and slide with surprising speed at times. Don’t count on your ability to dodge this hazard. It is best to reduce your risk by reducing time spent beneath frozen waterfalls. As we move forward, remember that Lunch Rocks is in the bullseye of the massive ice in Sluice which makes hanging out there a high stakes game of roulette.

The Lion Head Winter Route is still open. If skiing or riding in the Bowl and heading down, please walk down the Tuckerman Ravine Trail to Hermit Lake where you can then get on the Sherburne Ski Trail. The rope is up at crossover #3, about a half mile from Pinkham. Please respect the rope and move over to the hiking trail to avoid wallowing in mud.

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 caretaker at Hermit Lake Shelters.

Posted  8:00 a.m., Friday, April 21, 2017. A new advisory will be issued tomorrow.

Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2017-04-21