Avalanche Advisory for Sunday, April 23, 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. Use caution to avoid other spring hazards, particularly icefall. Lunch Rocks is in the direct fall line of significant ice and is not a safe place to linger.

 AVALANCHE PROBLEM: Our primary stability concern today will be loose wet sluff avalanches. These will be increasingly easy to initiate from beneath your skis or snowboard as the surface snow warms and softens through late afternoon. This heavy loose snow moving quickly downhill can easily knock you off your feet and cause an unexpected fall, so consider hazards that are below you when choosing your descent line. Thin wind slab exists in many areas from last night’s snow, but they should be small enough to not pose a problem to travelers. Additionally, the remote possibility of a large deep slab avalanche, with a sliding surface lubricated by flowing meltwater, will remain through much of spring. Of non-avalanche hazards, rapid warming makes increased likelihood of icefall a significant concern today.

WEATHER: It looks like a beautiful, warm day on the mountain. Light rain transitioned to snow yesterday evening, with less than one inch total at Hermit Lake and two inches recorded on the summit. Wind up to 50 mph blew out of the NW last night and will slacken to nearly calm conditions by late afternoon. Temperatures will rise all day, with a high in the mid 40’sF forecast on the summit. We will likely see temperatures in the 50’sF in the ravines.

 ADDITIONAL HAZARDS:

  • Icefall: A significant amount of ice exists high in our terrain, and it will fall down in very large chunks sooner or later with continued above-freezing temperatures. Particularly warm spring ski days like today are prime conditions for a person, or many people, to be caught in the path of massive icefall. Lingering below ice formations is definitely not a good plan. Lunch Rocks is in the direct fall line a large amount of ice that the sun will warm and weaken today, making it a particularly poor choice for a place to lounge.
  • Glide cracks (crevasses), moats and waterfall holes: These various types of deep cracks and holes are present and growing in our snowpack. Falls into these holes have claimed multiple lives in Tuckerman Ravine and command respect. While mostly visible, snow bridges likely exist as well over these features, of which the weight of a person could break easily. Give areas with obvious signs of open holes, like the Lip, a wide berth. Similarly, thin and weak snow exists in many areas undermined by flowing meltwater.
  • Long sliding falls: While this hazard will diminish slightly as snow softens through the day, a sliding fall that is difficult to arrest will be possible all day on our steeper slopes. The consequence of these falls continues to increase with increasing rocks and glide cracks present in our terrain. Don’t leave the ice axe and crampons at home.

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.

The Lion Head Winter Route is still open.

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., Sunday April 23, 2017. A new advisory will be issued tomorrow.

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

2017-04-23