Avalanche Advisory for Tuesday, April 18, 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.

AVALANCHE PROBLEM: There is little avalanche concern today. The trace of snow that arrived overnight coupled with another possible dusting today will likely not be enough to create new avalanche hazard. With colder temperatures, the isothermal snowpack has refrozen. This situation will make long, sliding falls the greatest threat today as the snow surface will repel attempts at self-arresting. If moving through steep terrain today, crampons, an ice axe, and sharp edges on skis will be necessary to staying safe. An out-of-control fall may land you in a newly opened glide crack or waterfall hole. Be mindful of your planned route of travel and what lies below.

WEATHER: The Summit and Hermit Lake both recorded 0.1” of new snow last night. Current weather at 6288’ is 13F with a 22mph NW wind. Clouds and summit fog should linger this morning along with the chance of a few upslope snowflakes. As high pressure moves in, clearing should take place this afternoon with wind shifting to the SW and diminishing further as temperature reaching into the 20sF. 

SPRING HAZARDS: As mentioned above, the objective hazards present on the mountain will be the largest threat today.

  • Long, sliding falls: Refrozen, spring snow provides the prime surface for a long fall. Stay sharp while moving around in terrain. One way to mitigate this hazard is to rope up while still in third class terrain and place adequate protection to guard against a fall. Any slip today could potentially turn into a slide for life and could put you into a glide crack or waterfall hole.
  • Crevasses, undermined snow, and large open holes: Water flowing under the snowpack creates holes and thin spots in the snow (the process of undermining) that are deep enough to injure or kill you. 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 and has a long history of acting in unpredictable ways. This particular hazard is best given a wide berth.
  • Icefall: This hazard will likely be on hold today as last night’s freeze should lock things into place. It is still worth keeping in mind as expecting the unexpected will result in safer decision-making.

Descending the mountain by skis? The Little Headwall is now more water than snow and is no longer recommended as a descent from The Bowl. The easiest and fastest descent is to hike down the Tuckerman Ravine Trail to Hermit Lake. The Sherburne is melting fast and much of the trail close to Pinkham has more dirt and grass showing than snow remaining. Removing skis for at least one section seems necessary at this point.

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., Tuesday, April 18, 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