Avalanche Advisory for Monday, April 17, 2017

This advisory expires at Midnight.

Huntington and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. Generally safe avalanche conditions exist. The Little Headwall is open water and not recommended as an exit from Tuckerman Ravine.

AVALANCHE PROBLEMAs the spring snowpack goes through the freeze/thaw process, avalanche problems start to take the back seat to other objective hazards. That being said, the mountain has been above freezing since Saturday morning relying on only strong wind speeds to cool things down. As depth of snow which a skier can push around increases, the potential for loose-wet avalanches rise. The steepest slopes that have seen less traffic have a greater likelihood of entraining enough snow to cause problems. With mindful steep-skiing techniques, most sluff-induced wet-loose avalanches can be managed. As the snowpack locks back up due to dropping temperatures, the loose-wet problem will be replaced by long, sliding fall hazard and possible wind slab. Snow showers in the afternoon of up to 2” may create isolated areas of wind slab. Due to decreasing wind speed and a small amount of snow forecast, these will likely be smaller in size and not pose significant problems.

WEATHER: Yesterday, roughly a third of an inch of water came in the form of rain. Today’s passing cold front will make for a dreary day on the mountain. Current weather on the Summit is a 32F with a W wind of 63mph. Wind speed will decrease throughout the day to the 40mph range while shifting to the NW as temperatures drop to 20F by evening. Upslope rain or snow may take place today; the type depending largely on the timing. Two inches of snow is on the higher end, though it will likely be less.

SPRING HAZARDS: In addition to the avalanche problems present on the mountain today, there are also the ever-present objective hazards to be on the lookout for.

  • Icefall: This threat is present this morning, though with fog shrouding the mountain, it may be difficult to see what ice lingers above you. Lunch Rocks is a poor place to spend time these days due to the ice in the Sluice appearing to be on the verge of letting go. As the temperature drops this afternoon, water will freeze and should lock things back into place, at least for the time being.
  • Long, sliding falls: Wet snow this morning will make a long fall unlikely to start the day. As temperatures drop through the day and the snow solidifies, crampons and an ice axe or sharp ski edges will be necessary to make travel safe.
  • Crevasses, undermined snow, and large open holes: Water flowing under the snowpack creates holes and thin spots in the 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. With possible new snow this afternoon, the smaller glide cracks may get covered, making identifying them difficult.

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  8:10 a.m., Monday, April 17, 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

2017-04-17