Avalanche Advisory for Sunday, April 3, 2016

This advisory will expire tonight at 12:00 midnight.

All forecast areas of Tuckerman Ravine have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Huntington Ravine is under a General Bulletin. 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: Today’s primary avalanche problem will be isolated pockets of wind slab. These pockets will likely be small and located in sheltered lee areas, like the Chute, Center Bowl and Lip, as well as the start zones of Left Gully and Hillman’s Highway. Winds will increase through the day, reaching the century mark around dark. As this happens, these pockets will reach peak sensitivity mid t0 late morning and then increase in strength as winds grow stronger. Many areas will be scoured to old surface. Safe travel will be difficult today as blowing snow and fog will make constant whiteout conditions.

WEATHER: Cold temperatures yesterday prevented any softening of the snowpack. Around dusk last night, the summit received 1.3″ (3.3cm) of new snow with Hermit Lake recording the same. Through the night, temperatures fell and winds increased to current summit conditions of 1F (-17C) and 51mph (82kph) winds. Winds are forecasted to increase steadily through the day, gusting to 130mph (209kph) by dusk. We may receive another trace to 2″ of snow today.

SNOWPACK: New snow yesterday evening fell on a well-frozen snowpack. Much of the new snow was heavily-rimed graupel and fell on lighter winds. Combine these factors with a denser slab forming due to increasing winds and we have a classic avalanche problem. However, only 1.3″ of new snow is available for transport. This morning, before winds really ramp up, I see the potential for isolated pockets to be reactive to a human trigger. As winds increase, these pockets will be hammered into very hard slabs, becoming less reactive. The potential for an additional 2″ of snow exists, but forecasts are leaning towards low accumulations. Safe travel in avalanche terrain today will require good visuals to see where pockets are developing and where winds are scouring down to the old surface. Due to blowing snow and cloudy conditions, visuals will be hard to acquire making travel difficult today.

Spring hazards you need to know about include:

  • Very icy conditions make any slips or falls in steep terrain a very dangerous event. Stopping a fall can be near impossible on hard refrozen rain crusts. Using crampons and and an ice axe is helpful, but not foolproof. The best way to mitigate this hazard is to avoid steep icy slopes, i.e. wait for a better day to get into steep terrain.
  • Crevasses, moats and waterfall holes – Multiple waterfall holes have opened in the Lip, including the open book hole responsible for a hiker fatality April 1, 2012, but they may be hidden from view by newly wind loaded snow. In other areas, large volumes of water is flowing under the snow pack, which has created small holes or thin snow bridges.

The Sherburne Ski Trail is now closed at #7, allowing about 2/3 mile of skiing from Hermit Lake. Expect ice with a dusting of new snow.

The Harvard Cabin is closed for the season. The only camping permitted in the Cutler Drainage will be at Hermit Lake Shelters.

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 8:30 a.m., Sunday, April 3, 2016. A new advisory will be issued tomorrow.

Helon Hoffer and Jeff Lane, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2716

2016-04-03