Avalanche Advisory for Sunday, January 14, 2018

Huntington and Tuckerman Ravines have LOW avalanche danger. Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. The Little Headwall has again become a waterfall and is not rated.

 AVALANCHE PROBLEM: A solid refreeze of our heavily wetted snowpack has greatly increased stability which will hold through this forecast period. Natural and human triggered avalanches are unlikely at best. If you’re in our terrain today, a number of other hazards should make avalanches a lesser concern:

  • Long sliding falls are all but certain if you lose your footing high on a steep slope. Crampons, ice axe, and your ability to use them are essential for travel on snow slopes today. Microspikes are an effective tool on icy trails but are no substitute for crampons on firm snow slopes. Realize that the hardness of surface snow will make arresting a fall with an ice axe very challenging and that recently exposed rocks elevate the consequences of such a fall.
  • Undermined snow and water running under snow and ice is a concern with water continuing to flow despite cold temperatures. Watch for low areas that could be draining water, listen for water flowing under the snow and ice, and remember that significant water flows down our ice climbs.
  • Ice dams and blowouts of ice are common in conditions like this when significant water flows under ice in ice climbs. These can cause a myriad of problems and have been the source of fatal accidents.

 WEATHER: Seasonable cold temperatures have returned following several days of very warm and wet weather. Over 48 hours of above freezing temperatures and 3” or more of rainfall wreaked havoc on the mountain. Areas farther west saw several inches of snow yesterday, but we received only negligible amounts of frozen precipitation. Expect today to be clear and cold with temperatures in single digits F. Summit wind should stay in the 20-30 mph range. Tomorrow is forecast to bring slightly warmer temperatures, similar wind speeds, a few more clouds, and no precipitation.

SNOWPACK: The significant rainstorm of the last few days drastically changed conditions top to bottom on the mountain. The waterfall area of the Lip produced a massive wet snow avalanche that entrained a significant amount of snow and fully covered the floor of Tuckerman Ravine with debris. A strong refreeze since yesterday afternoon has stabilized our snowpack, but this avalanche serves as an excellent reminder of what heavy rains on snow can produce. Outside of this avalanche debris, much of our terrain hold a hard, icy, and fairly smooth snow surface. Coverage has decreased with more rocks and bushes exposed, but after a snowstorm or two the skiing shouldn’t be bad.

The John Sherburne Ski Trail has large areas where flowing water melted all snow. We highly recommend that skiers and snowboarders avoid it until filled in with more snow. For travel on foot, areas of water flowing across and down the trails had similar though less drastic effects. The Lion Head Winter Route remains open, though significant loss of snow will make travel challenging.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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 caretakers at Hermit Lake Shelters or Harvard Cabin.
• Posted 8:00 a.m., Sunday, January 14, 2018. 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

2018-1-14