Avalanche Advisory for Friday, April 11, 2014

This advisory expires at midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. Sluice, Lip, Center Bowl, Chute and Left Gully have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have 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 when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM:  Heat penetrating into the snowpack, as well as some more rain, has the potential to weaken remaining deeper weak layers today. This means that Persistent Slabs are our primary avalanche problem. The Lip, Center Bowl, Chute and, to a lesser extent, Left Gully are the areas that carry the greatest risk. Though the probability of triggering one of these slabs is low, I would not want to be caught by the resulting debris. Minimize your exposure to this risk by traveling out of the fall line. Thin Wet Slabs from wind slabs which developed in the past 36-48 hrs in Moderate rated areas are also a potential concern though they carry less consequences than the deeper weak layers. Wet Loose sluffs are likely and will happen on most steeper terrain today.

WEATHER: The summit recorded .14″ of freezing rain last night with nothing in the collection can at Hermit Lake. Temperatures at Ravine elevations have been around 40F for the past 24 hours. Today’s forecast calls for more shower activity this morning before limited clearing begins this afternoon. West winds will drop from 50-70 mph to 30-45 mph through the day. Temperatures around 20F tonight will bring a good freeze up to restore the upper snowpack. Generally a warm but gloomy day is on tap.

SNOWPACK: Avalanches have mostly cleaned out the January 11 rain crust/facet layer but smaller areas still exist as do other deep wind slab interfaces. This 24 hr period of warm temperatures and rain is a pretty strong stressor so heat may reach these deeper layers for the first time. Shadier aspects have certainly not seen this degree of heating yet and many of the warm sunny days we have seen so far this year did not wet the snow much deeper than 40-50 cm down. This leads me to be suspicious of the Moderate rated slopes. This is the kind of hazard that can potentially reward a person who habitually practices safe travel techniques and minimizes exposure time. Skiing one at a time, climbing the extreme margins of gullies, and not waiting in the runout for others to descend are all wise choices.

OTHER HAZARDS: Slopes and gullies can change from soft and forgiving to icy and refrozen depending on subtle variations in aspect and snowpack. This can limit penetration of boots or skis therefore crampons and an ice axe are recommended for travel on steep slopes. Micro-spikes and other creeper style traction devices may be helpful on some lower angle trails, but they do not provide the security of crampons. Be prepared to handle steep, firm snow and fast, icy surfaces. Icefall can be a problem at times and though we are not into peak heating and associated icefall hazard yet, we are definitely seeing daily cycles of smaller icefall events. Huntington Gullies can spawn rockfall pretty readily with this amount of warmth and rain.

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. 4-11-2014. 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

2014-04-11 Print friendly