Latest avalanche advisory for Mount Washington’s Cutler River Drainage – Tuckerman and Huntington Ravines

General Bulletin for Tuckerman and Huntington Ravines

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.

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 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

2018-04-25 General Bulletin

Avalanche Advisory for Tuesday, April 24, 2018

Huntington Ravine has MODERATE and LOW avalanche danger. Yale, Central, Pinnacle, Odell and Escape Hatch have Moderate avalanche danger. Evaluate snow and terrain carefully to identify features of concern. All other forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger.  Right Gully, Sluice, Lip, Center Bowl, Chute, Lower Snowfields and Hillman’s Highway have Moderate avalanche danger.  Evaluate snow and terrain carefully to identify features of concern. All other forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features. The Little Headwall has undermining snow and open water.

AVALANCHE PROBLEM: Wet Slab is becoming our primary avalanche problem and will increase in likelihood with continued warming through the day. Wet slab avalanches are characterized by uncertainty, with the timing of peak instability for slab avalanches quite difficult to pin down. Our warming wind slabs that are becoming wet slabs also lend uncertainty to potential size of avalanches today, with large avalanches remaining a possibility. As surface slabs warm they may ultimately lose cohesion and be more likely to produce loose wet avalanches, or sluffs. Both of these avalanche problems will be most prevalent on sun exposed slopes. Areas receiving Low avalanche danger ratings today are rated so for limited potential size of avalanches.

In addition to avalanche concerns, spring hazards are emerging in the ravines. Icefall will be a key hazard resulting from today’s warm temperatures and solar heating. Areas under southerly facing ice, like Lunch Rocks, are particularly unwise places hang out. Melt water flowing under ice and potentially building up pressure will make ice dams a concern for climbers. Undermined snow will result from flowing melt water, with open holes and weak snow bridges over streams a potential concern in a number of locations including the Little Headwall.

 WEATHER: Yesterday finally felt like spring up here.  The summit hit a high of 34F with light and variable winds.  Overnight the temperatures only dropped to 30F with winds increasing to 40mph out of the W.  Yesterday Hermit Lake saw a high of 58F with light and variable winds.  Today we expect temperatures to stay slightly above average with a summit high around 40F.  The winds should increase slightly from yesterday to 25-40mph out of the W shifting to the SW.  This evening we expect unsettled weather to return which will bring precipitation that is currently predicted as an all-rain event.

SNOWPACK: Our upper snowpack consists of wind slabs formed late last week on a robust melt-freeze crust. These old wind slabs vary greatly in thickness, from several inches to several feet, and the older melt-freeze crust is exposed in some areas. Instabilities below this crust should not be of concern today. Wet slabs as an avalanche problem are characterized by uncertainty, and today is no exception. Instability will be primarily driven by warming of the upper snow pack.  This can weaken bonds between layers before the snow becomes truly wet, with melt water lubrication becoming a further cause of instability as warming continues. Surface slabs on southerly aspects may experience enough loss of cohesion though warming for loose-wet sluffs and point releases to become more likely than wet slabs, but again, uncertainty rules the day. Much of our terrain remained at or above freezing last night, furthering the warming of our snowpack. Skiing and riding should be best this morning and become increasingly sloppy and sticky as the day progresses. Where present at the surface, the old crust will be softened and likely provide the best turns. Wet slabs may be a tricky avalanche problem to manage, but the quality of skiing and riding generally deteriorates as instability increases on days like today. It’s a great day to get in and out of terrain relatively early, both to manage the avalanche problem and to score the best conditions.

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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.
• Posted  8:00 a.m., Tuesday, April 24, 2018. A new advisory will be issued tomorrow.

Ryan Matz/Amanda Tulip, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2018-4-24