Avalanche Advisory for Tuesday, March 24, 2015

This advisory expires tonight at 12:00 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. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

All forecast areas of Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEM: Wind slab is the primary avalanche problem today. This problem is focused on the midsection of Tuckerman, from the Sluice through the Chute. As far as a Moderate rating goes, the likelihood of triggering a slide is on the lower end of the rating’s range, but not stable enough to warrant a different rating. Additionally, the stakes are raised quite a bit as we would expect the size of an avalanche here to be large and destructive. Other areas rated Low have good stability thanks to very strong winds hammering the slopes into submission. Be watchful for isolated unstable pockets in strongly sheltered areas such as the Lower Snowfields.

WEATHER: Very few people ventured up into the ravines yesterday, and for good reason. Temperatures spent much of the day below zero degrees Fahrenheit while summit winds blew strong throughout the day. From Sunday and into Monday morning, winds had been gusting over 100mph for more than 24 hours. They started to subside yesterday and have come down to near calm levels for this morning. Today you’ll have relatively light winds and sunshine but wintery temperatures will keep it from feeling too much like spring.

SNOWPACK: A good portion of the terrain in Tuckerman and Huntington is firm wind-hammered surfaces. These offer good stability, but not great skiing or riding conditions. If you’re heading into one of these Low rated areas, the climbing will be easier and safer if you have an ice axe and crampons. Speaking of wind-hammered surfaces, the Sherburne trail was scraped clean down to old hard snow for much of its length. My mountaineering boots barely scratch the surface when walking on it.

The focus of the avalanche problems in Tuckerman are found under the ice in the Center Bowl and in the Lip area. The rim of the ravine was blown clean, and the lower angle transition to the floor is a mix of scoured and wind-hammered. It’s the elevation right in the middle where it’s most steep that you will want to be watching. You can expect firm surfaces and strong slabs in the upper layers, but what lurks beneath the surface is where the problem resides. Depending on your exact location, you may see weak interfaces between wind layers, faceting, or recently hidden ice, rocks, or bushes that have created shallower weak spots.

Sunshine may have an effect on steep south facing slopes, but I don’t expect this to be too great or have a significant effect on stability.

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 7:45 a.m. Tuesday, March 24, 2015. A new advisory will be issued tomorrow.

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