Avalanche Advisory for Sunday, April 10, 2016

This advisory expires at midnight.

Tuckerman Ravine has MODERATE and LOW avalanche danger. The Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist in certain terrain features within these forecast areas. All other forecast areas have Low avalanche danger.  Natural and human-triggered avalanches are unlikely except in isolated pockets. The Lobster Claw, Little Headwall and Lower Snowfields are not posted due to lack of snow.

Huntington Ravine is under a General Bulletin for the remainder of the season. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Today’s avalanche problem is wind slab. Winds ramped up last night, further scouring some areas while loading new snow in others. There is still a fair amount of icy old surface visible through the summit fog this morning but the larger pillows scattered around are large enough in the moderate rated areas to create concerns for human-triggered avalanches. Yesterday, wind slabs that developed after the rain event with 6” inches of new snow (measured on the summit) proved to be pretty well bonded to the rain saturated and refrozen snow beneath. Cold temperatures last night certainly didn’t allow for settlement or bonding and there is a good chance that some faceting may have reversed the trend towards stabilization. If you venture into the terrain, be wary of the size of the wind slabs and stick to the old surface when possible.

WEATHER: Winter weather is taking the helm again today and will likely continue to steer us away from good spring skiing conditions. The mercury stands at 5F at Hermit Lake right now with -3F on the summit and a harsh NW wind blowing at 60 mph on the summit. Though the forecast is again calling for mostly clear skies today, we are not counting on much of a warm up at Ravine levels today. Summit temperatures should rebound to the mid-teens later in the day with slightly relaxed winds from the west at 30-45mph. Temperatures will be slightly warmer and winds lower in the Ravines but will not allow much, if any, warming of the snowpack.

SNOWPACK: Winds ramped up last night and further scoured Left Gully with signs of scouring across much of the Center Bowl area. Newly deposited, wind blown snow filled yesterday’s tracks in the Lip and built larger pillows of snow below the ice. Chute also gained snow, primarily above the choke . Some of the wind slab is likely to be on the firm side but I would test for weak interfaces and consider the results before venturing onto a steeper slope with large areas of the wind slab. Remember that hard slabs can often appear stubborn with moderate to hard results in stability tests. Though this indicates that triggering may be more difficult it doesn’t rule out a crack propagating. A few of the wind slabs in the Lip and Chute could bury a person but it’s more likely that a human-triggered avalanche in other areas would take someone for a very long ride through traumatic terrain.  Besides avalanche hazard these are very important points to remember today:

  • Long sliding falls – Crampons, an ice ax, and the experience and skills to use them effectively are required to travel safely in steep terrain. Snowshoes and microspikes are absolutely no substitute. However, arresting a fall on a steep icy slope can be practically impossible even with an ice axe.
  • Crevasses, moats, and waterfall holes – Water flowing under the snow pack creates holes and thin spots in surface that are deep enough to injure or kill you. New snow can drift and obscure the openings.

The Sherburne Ski Trail is now closed one third of the way down from Hermit Lake. Expect water ice under a dusting of new snow.

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 caretakers at Hermit Lake Shelters.
  • Posted 7:40 a.m., Sunday, April 10, 2016. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2716