Tuckerman Ravine has MODERATE and LOW avalanche danger today. Lobster Claw, Right Gully,The Sluice, the Lip, Center Bowl and Chute have MODERATE avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Of these, the Lobster Claw and Right Gully are at the lower end of the Moderate rating. Left Gully, Hillman’s Highway, the Lower Snowfields and the Little Headwall have LOW avalanche danger. Natural and human triggered avalanches are unlikely in those locations. Watch for unstable snow on isolated terrain features.
Huntington Ravine has MODERATE avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully. South Gully and Escape Hatch are at the lower end of this rating.
The mountain has cleared already this morning as of 7:00am. This will allow a full day of heating today on south facing aspects today and contribute to our concerns about human triggered avalanches to warrant a Moderate rating. Yesterday’s new snow mostly blew down into the mid-elevation start zones of lee gullies. Steeper parts of these areas are the focus of concern today. The concern is generally limited to these recent new snow layers losing strength as they warm and possibly fracture and fail. A shallow slab could entrain more snow on it’s descent but do not forget the poorly bonded interface at the mostly deeply buried ice crust . In Tuckerman Ravine, I would be most concerned about the surface slab problem in the climber’s left fork of Lobster Claw, the large climber’s left hand pillows near the top of Right Gully, the steepest section of the Sluice and the Lip. The belly of Right Gully and the main gully in Lobster Claw received a lot of “skier control work” recently which generally cut up the slab but the steeper drop-ins in Right Gully and the climber’s right fork of Lobster Claw could release if the right trigger is applied in the right spot.
Another concern of a different nature is the pooled rimed snow which has sluffed over the ice in Center Bowl and the upper part of Chute and which may lurk elsewhere. An experienced party wisely abandoned an attempt to ski the Chute yesterday when they began to wallow in waist deep snow on their way through the narrow, choke point which avalanched recently and has now reloaded as a result of this “sluff loading”. Left Gully should provide dry snow for skiing with some windloaded pockets here and there. Remember that our areas rated at Low remain exposed to hazards from above. For example, a poorly chosen approach to Left Gully puts you in the runout of Chute and sections of the Lower Snowfields are threatened by the Duchess so stay alert plan for worst case scenarios.
In Huntington, fairly well developed snowfields exist near the top of Damnation, the mid section and adjacent to the Harvard ice bulge in Yale, as well as below and above the first ice pitch in Central. Look for sluff loading in Pinnacle at the base and to a lesser extent in the mid-section. More easily avoidable pockets of slab on Odell, South and Escape Hatch also exist.
This is the first spell of intense warming that we have had for some time so all the issues you’d expect from rocks, ice and slabs of snow heating should be on your radar today. The other issue will be the amount of human triggers overhead who may not see you or may not know how to avoid hazards. People innately seek the comfort of others in steep terrain so don’t be distracted from safe travel guidelines by others who may be taking uncalculated risks by booting up avalanche tracks.
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 at 8:30a.m., March 30, 2013. A new advisory will be issued tomorrow.
Frank Carus, Snow Ranger USDA Forest Service White Mountain National Forest (603) 466-2713 TTY (603) 466-2856