Avalanche Advisory for Monday, January 15, 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: The significant melt freeze event of the past few days coupled with continued cold temperatures greatly reduced instability in our snowpack. Natural and human triggered avalanches are unlikely today, with other hazards currently of greater concern for those travelling in our terrain. The following hazards are particularly noteworthy today:

  • 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 on our ice climbs in conditions like this when significant water flows under ice. These can cause a myriad of problems and have been the source of fatal accidents. Be particularly cautious of screw, tool, and foot placements in regards to this issue.

WEATHER: It’s a colder morning at Pinkham than at the summit, with a temperature inversion holding air just below 0F at low elevations. It’s currently 11F on the summit. Temperature is forecast to increase by just a few degrees on the summit today and decrease to around 0F tonight. Southerly wind approaching 30 mph at the top of the mountain should feel relatively calm in the ravines. Partially cloudy skies should become mostly cloudy tonight. Tomorrow brings increased cloud cover as a system approaches late in the day with potential to give us a few inches of new snow by Wednesday morning.

SNOWPACK: The strong temperature swing Saturday that followed our significant rainstorm resulted in hard refrozen surface snow and generally stable conditions throughout our snowpack. As mentioned above, this means full on slide for life conditions in our steep terrain. Snow depth and coverage has decreased significantly. North, Damnation, Yale, South, and Escape Hatch gullies in Huntington Ravine do not hold continuous top to bottom snow. The same is of course true for the open stream that is the Little Headwall. Snow in other areas has become quite narrow, and the tops of a number of gullies have melted to rock. In Tuckerman, Right Gully was hit particularly hard while other areas faired reasonably well and continue to hold top to bottom snow. It’s a drastic shift from the plentiful dry snow of early last week and from the conditions which produced Friday’s massive wet avalanche in the Lip of Tuckerman Ravine.

The John Sherburne Ski Trail has a large area where flowing water melted all snow. Combined with firm conditions and a rough refrozen snow surface in places, it’s not a great ski option. 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 with varied conditions including snow, ice, dirt, and rock.

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 7:30 a.m., Monday, January 15, 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

2018-1-15