Posted 8:10a.m., Saturday, February 12, 2011
Tuckerman Ravine: The Lobster Claw, Sluice, Lip, Center Bowl, and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Right Gully, the Chute, Left Gully, the Lower Snowfields, and the Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely.
Huntington Ravine: All forecast areas of Huntington have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.
Avalanche conditions in the ravines today are similar to where they’ve been for the past couple days, with a couple of areas’ ratings dropping from Moderate to Low and a little bit of weather coming in toward the end of the day that might push things back up the scale again. For the better part of the day conditions will remain where they currently are; however, we are expecting up to an inch of new snow along with strong W winds, particularly in the late afternoon. Depending on exactly how much new snow falls, this may increase the avalanche danger in many of the areas currently rated at Low. So before we get into what’s currently out there, take the idea of changing conditions and stash it in the back of your mind so that if you’re out later in the day when conditions begin to change you won’t get caught unaware.
Both ravines feature a dominant surface layer that is leftover from very strong winds midweek. Tuesday night wind gusts exceeded 100mph and they stayed strong in the following days. This left a lot of wind-hammered slab in many places. This hard slab has a great deal of strength to it, and in general it’s strongest in locations that are thickest and hardest. The locations that didn’t feel the full force of the winds are the ones where the slabs that built are softer, and these relatively softer slabs are also relatively weaker and hold greater potential for human triggering. Locations where this is most prominent include strong lee areas in Tuckerman such as under the Headwall ice, the lower Lip, and the Sluice. In Huntington you’ll find examples in areas such as the start zones of Escape Hatch and South Gully, and under rock buttresses at the tops of the approaches. Good route finding is important but may prove challenging today as clouds lower and new snow helps to obscure your vision.
- 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.
- This advisory expires at midnight. 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