Avalanche Advisory for Sunday, April 16, 2017

This advisory expires at Midnight.

Huntington and Tuckerman Ravines have LOW avalanche danger. Natural and human triggered avalanches are unlikely. Generally safe avalanche conditions exist, but watch for unstable snow on isolated terrain features. The Little Headwall is not forecast as it is now dominated by a raging waterfall. It contains weak snow bridges and other undermined snow hazards that could break under your weight, landing you in flowing water which could pull you under downstream snow. Many skiers are wisely choosing to walk down from Tuckerman Ravine to Hermit Lake as a result.

 AVALANCHE PROBLEM: Our snowpack is generally stable due to freeze/thaw cycles that have occurred over the past week. Loose-wet sluff avalanches remain a possibility, particularly on steep slopes that have seen minimal skier traffic over the past two days. These heavy wet sluffs are easy to initiate with the snow you push downhill from your ski turns, and have the potential to pull your feet out from under you. Consider the consequences of your terrain choice, you don’t want sluff to cause you to fall above a cliff or other hazard. Our snow surface did not experience a full refreeze last night due to warm temperatures, but high wind overnight has driven some surface cooling, leaving our snow firmer than yesterday evening. Softening should occur with warming temperatures through this afternoon.

WEATHER: Happy Easter! Well, sort of. Today won’t be the classic spring ski day we saw yesterday. Cloud cover and wind up to 90 mph on the summit have dominated overnight, with a quarter inch of rain falling and temperatures remaining in the mid to upper thirties. Through the day, temperature is forecast to rise to near 50F on the summit, with the ravines likely warmer. Elevated westerly wind, slackening briefly to 40 mph before again approaching the century mark by dark, could make it feel much colder. Thunder storms are likely this afternoon and into the evening, and we could receive another quarter inch or more of rain with the heaviest showers starting early afternoon.

SPRING HAZARDS: As our snowpack stabilizes this time of year, a number of other hazards emerge. That said, the potential for a slab avalanche is not entirely eliminated, so we continue to carry a beacon, shovel, and probe. We encourage you to do the same. Be sure to respect the following hazards as well:

  • Icefall and rockfall – Warming, of course, begins to melt the significant ice features on the mountain. This ice tends to fall in large to very large pieces, potentially much bigger than you, which you obviously don’t want to coming down on top of you. Lunch Rocks is in the direct fall line of such large icefall that will occur at some point this spring. Melting also loosens rock high on the mountain, increasing the chance it will fall naturally or be kicked down by someone above you.
  • Long sliding falls – While our snow surface is not particularly icy this morning, it is plenty firm enough to allow a high-speed sliding fall. A number of such falls with several resulting injuries have occurred over the past two days. Respect the consequence of a fall on any slope you choose to climb or ski. Crampons are highly recommended in steep terrain. Snowshoes and microspikes are no substitute
  • Crevasses or glide cracks, moats and waterfall holes – Warm water flowing under the snow pack creates holes and thin spots in surface that are deep enough to injure or kill you. A number of glide cracks have opened over the past few days, approaching the size that a person could fall into. Be on the lookout for these to continue to grow.

The Harvard Cabin is closed for the season. We will continue posting advisories there as long as it is logistically feasible or until the ice melts out and we move to a General Bulletin.

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 16, 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

2017-04-16