Avalanche Advisory for Monday, May 11, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Huntington Ravine is under a General Advisory  you will need to do your own snow stability assessments. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: We are into a period of time with a very stable snowpack. Avalanche problems take distant a back seat to the hazards below.

WEATHER: Expect a dreary day on the mountain. Rain and drizzle, thick fog, and temperatures falling in the afternoon would be enough to make me think about rescheduling my ski day or summit hike. Don’t forget that there will also be a chance of a thunderstorm in the afternoon. See the Mt. Washington Observatory’s full forecast here for more information.

FALLING ICE: Falling ice remains a substantial and imminent hazard. We are at peak ice fall season. Massive blocks still cling to the headwall cliffs as well as on the cliffs directly above Lunch Rocks. Avoiding Lunch Rocks will dramatically reduce your overall icefall risk. If fog obscures the ravine today, the chances of seeing falling ice before it is too late become much less. If you must be in the ravine today, your best bets will be to go to locations with lower risk of icefall, such as Hillman’s or Left Gully.

UNDERMINED SNOW: This hazard develops where the snowpack has a stream or river of meltwater running beneath. In general, areas with the largest volume of flowing water will create the most undermining with a weak snow bridge above. The main waterfall hole to the climber’s left of the Lip has grown considerably with recent melting. A fall into this waterfall hole or other areas with undermined snow can be fatal. Give a wide berth to this and other holes in the snowpack!

CREVASSES: Crevasses are growing in many locations. The number and size of crevasses is greatest in the Lip and Sluice, but other locations have these slots opening up as well (e.g. the upper part of Chute). These can be covered by hidden breakable snow bridges. Many of these are wide enough to fall into and they are probably much deeper than you think.

THE BOTTOM LINE: Hillman’s Highway and Left Gully are the longest continuous snow slopes and have lesser objective hazard than the Sluice, Lip, Center Bowl, and Chute. The opportunities for skiing down out of the bowl or on the Sherburne are gone. The Little Headwall is fully melted out and the Sherburne is now closed.  Please do not walk on the ski trail. Doing so contributes to erosion of soil off the trail and will leave your boots caked with mud.

We will be opening the Lion Head summer trail this week. This trail does traverse a steep snow slope and has many patches of ice, so come prepared.

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 Mount Washington Volunteer Ski Patrol, or the AMC at the Pinkham Notch Visitor Center and Hermit Lake.
  • Posted 7:25 a.m., Monday, May 11, 2015. A new advisory will be issued tomorrow.

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

2015-05-11