Avalanche Advisory for Saturday 2-23-2013

This advisory expires at 12:00 midnight, February 23, 2013.

Tuckerman Ravine has MODERATE and LOW avalanche danger. The Sluice, Lip, and Center Bowl have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas in Tuckerman have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

Huntington Ravine has MODERATE and LOW avalanche danger. Central Gully has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas in Huntington have Low avalanche danger. Natural and human triggered avalanches are unlikely.

We’ve been watching the developments of this incoming winter storm with eager anticipation, but the latest news is that accumulating snow is not expected until after dark today. For today, the majority of the snow stability issues you’ll content with are the results of approximately 10” of snow that fell on the mountain mid-week.

In Huntington, much of this snow got blown out of the gullies, leaving behind well-scoured surfaces, many with raised remnants of footprints. Aside from the usual isolated unstable pockets in strongly protected lee areas, the biggest concern is the snowfield between the top of the Fan and the Central Gully ice bulge. This lies in the lower end of the Moderate rating, but it does extend from wall to wall in the gully so it would be difficult to get around it. The other big issue in Huntington is found at the top outs of many of the climbs, particularly Central, Yale, Damnation, and North. There simply isn’t much snow at the tops of these climbs, so be prepared for poor protection, rock scrambling, and if you’re lucky, frozen turf to swing into.

Tuckerman Ravine yesterday felt like being in a giant solar collector. Full sunshine, light winds, and mild temperatures made for very comfortable conditions, yet for some reason very few people ventured above the floor of the ravine. Again, the biggest concerns in Tuckerman are from slabs developed on Wednesday and Thursday. Today, the bulls-eye for instability will be centered on the areas around the Lip and under the ice in the Center Bowl. Warmth and solar energy helped to stabilize slopes facing into the sun, such as Right Gully, but in the Lip and Center Bowl the aspect is just off enough that the sun provided only a glancing blow. Hangfire above existing crown lines and reloaded bed surfaces will harbor instabilities at weak layers and interfaces beneath the snow surface. In many locations posted at Low, you should be aware of the potential for unstable slabs in isolated terrain features. Examples include on the steep climber’s left side walls of Right Gully and Lobster Claw (similar aspect and slope angle to the Lip), above the narrows of the Chute, and at the top climber’s right side of Hillman’s Highway. If you find one of these pockets, the avalanche may be small, but consequences will be large.

Light snowfall is currently underway on the mountain. Pay attention to accumulations! While we are not expecting much during daylight hours or early evening, if our expectations are off, we will see avalanche hazard on the rise before this advisory expires. The first places I’d expect to see rise are locations rated Low, particularly those with N and E aspect such as Left Gully or Odell Gully. Also expect elevated danger ratings tomorrow due to the storm.

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 or the Harvard Cabin.
  • Posted 8:00 2-23-2013. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2013-02-23 Printable