We are no longer issuing avalanche danger ratings for Tuckerman and Huntington Ravine this season. However, we will continue to provide snowpack and weather information two or three days per week for these areas. Avalanches, falling rocks and ice, undermined snow, large glide cracks and icy refrozen surfaces will remain a threat in and below steep terrain as long as snow remains in the mountains. Spring weather brings about rapid changes to the snowpack and changes objective hazards accordingly. Remember to ski, climb or hike the snowpack and weather conditions that exist and not a date on the calendar!
Yesterday, the temperature on the summit reached 43 F, with 62 F at Hermit Lake. Light wind from the southwest around 20 mph made it feel downright hot with sloppy snow conditions the result, particularly in strong solar aspects. Cloud cover moved in overnight and 1-1.5” of rain is forecast through Thursday. Temperatures all the way to the summit will remain mostly above freezing though they may dip down near freezing for short periods at the highest elevations. Snow or freezing rain may mix with rain at times but it doesn’t appear as if the snow will accumulate. The heavy rain and warm temperatures will speed the onset of spring hazards including the potential for large wet avalanches in limited areas, particularly the Lip. The recent warm, sunny days weakened the upper snowpack and threatened wet slab avalanches in a few areas though avalanches were limited to widespread but generally harmless wet loose sluffs. The heat also brought settlement as melt water percolated through the snow and rounded the existing snow grains. Continued warm temperatures with heavy rain will further saturate the snow and maintain the threat of natural avalanche activity in a few areas. Drier conditions and a return of freezing temperatures, possibly Saturday night, will improve stability and begin a corn snow cycle.
Remember to keep the following hazards in mind as you plan your route:
- Icefall: Over the years many people have been severely injured or killed by falling ice in Tuckerman. The most hazardous locations are in the center and right side of the ravine, including Lunch Rocks, the Sluice, Lip, and Center Bowl. Warm weather and rain increase the potential for icefall to occur. There is a lot of ice hanging on the cliffs in the Sluice and the Headwall. Avoid spending time in high risk areas such as on the floor in the fall line of the headwall ice or at Lunch Rocks.
- Glide cracks and waterfall holes: As the snowpack gradually gives way to gravity and creeps downhill, it pulls away from cliffs and leaves gaps. These gaps are the horizontal cracks that will soon appear in the steep terrain, most noticeably in the Lip. These can be surprisingly deep and are a place you don’t want to fall into. The waterfall hole in the Lip is a unique hazard. In addition to being a large hole, the flowing water has spawned large and destructive wet slab avalanches in the past.
- Undermined snow: Meltwater flowing under the snowpack melts away the snow above, creating thin bridges of snow that can collapse. These are beginning to emerge the tops of gullies (particularly on south-facing slopes) and in areas that have streams running, like the Little Headwall. The sound of running water can sometimes be heard under the snow and is a good indicator of this hazard. Breaking through weak snow into one of the larger water courses could be fatal if you become trapped.
- Long, sliding falls: Part of what makes spring skiing so great is the melt/freeze cycle that creates corn snow. The cycle begins when the snowpack freezes at night or in the afternoon shade on cooler days. The refreeze creates a hard surface that is nearly impossible to arrest a fall with skis or an ice axe. Refrozen snow can cause trouble for those looking to get “just one more run” at the end of the day.
Though icy, the Winter Lion Head Route remains the preferred option for summit hikers due to the fall and avalanche hazards at the traverse near treeline on the summer trail.
• 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 Mount Washington Volunteer Ski Patrol or the caretakers at Hermit Lake Shelters.
• Posted 8:00 a.m., Wednesday, April 25, 2018. A new advisory will be issued tomorrow.
Frank Carus, Lead Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856