Avalanche Advisory for Saturday, March 5, 2016

Tuckerman Ravine has Moderate and Low avalanche danger.  Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely but human-triggered avalanches are possible. Evaluate snow and terrain carefully. Lobster Claw, Right Gully, Left Gully and Hillman’s Highway have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. The Lower Snowfields and Little Headwall are not forecasted due to lack of snow though the sluff pile beneath Duchess has grown recently.

Huntington Ravine has Moderate and Low avalanche danger. Central Gully has Moderate avalanche hazard. Human-triggered avalanches are possible in this location though natural avalanches are unlikely. All other forecast areas have Low avalanche danger. Natural and human-triggered avalanches are unlikely but continue to watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM:  A widely variable wind slab issue is our avalanche problem today. Firm (P) wind slabs exist as hangfire above crownlines as well as in reloaded areas down slope of the crowns. In some areas, these slabs have a very soft weak layer beneath. In addition to this problem, the 2-3cm of very light density new snow, that fell yesterday and last night, will add complexity to the mix of hazards. If forecast gusty winds play out and continue to move the new snow, more wind slabs will develop. These wind slabs are likely to be sensitive to a human-trigger due to the light density of the potential weak layer. Though the calendar and valley weather may lead you to believe that spring like conditions should exist in our terrain, they don’t. Expect a complex avalanche hazard today.

 WEATHER: 2-3cm of very light snow fell last night on light winds. This snow is laying around in the alpine waiting for the increase in wind speed that is forecast for the morning. At this hour, summit wind speeds in the 20 mph range are already creating some visible plumes. Expect winds to increase this morning to the 25-40mph range with gusts to 50 mph shifting from the N to the NW. During the last 48 hours, temperatures have struggled to reach into single digits and are forecast to remain cold (5F) through today. These cold temperatures have not contributed to a stabilizing trend.

SNOWPACK: Crown lines from avalanche activity remain visible in the Lip, across the Center Bowl and near the top of the upper left fork of Hillman’s with debris running from Left Gully across the floor. Signs of avalanches from Central through South gully also highlight Wednesday’s avalanche cycle following the 8” of snow on south winds shifting to the west. Northern gullies received a good scouring with Central, Pinnacle, Odell and South receiving a mix of scouring due to wind and avalanche activity. Expect mostly firm (P) slabs but with a 4 finger to fist hardness weak layer in isolated areas so maintain your safe travel discipline throughout the terrain. Older, gray looking snow from the Feb 3-4 melt freeze crust exists in areas too and will provide a more sure-fire stable surface to travel on, though self-arresting on this icy surface would be challenging at best.

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 or the Harvard Cabin.
  • Posted 8:30am, March 5, 2016. 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