Avalanche Advisory for Monday, April 11, 2016

This advisory expires at midnight.

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. Right Gully has MODERATE avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. All other forecast areas of Tuckerman Ravine have CONSIDERABLE avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential. Lobster Claw, Lower Snowfields and Little Headwall are not posted due to lack of snow.

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 avalanche problem will be Wind Slab transitioning to Wet Slab. Avalanche hazard will increase throughout the day due to forecasted weather. Wind slab will develop today as up to 4” of forecasted snow loads into the ravine on increasing winds. As the day progresses, snow will transition to rain, changing our primary problem to wet slabs. Rain on the wind slabs will weaken them and increase the likelihood of natural avalanches. Travel in avalanche terrain today will require cautious route-finding with natural avalanches in several places being possible. The wind slabs which formed Saturday night in Sluice across to Chute, and were active yesterday in some areas, are still in play and would be likely spots for a larger natural avalanche to occur.

WEATHER and SNOWPACK: Snowfall began on the summit in the wee hours of the morning. Dry air in place from the high pressure system that just exited allowed falling precipitation to evaporate by the time it reached lower elevations so don’t be too surprised by the hazard forecast this morning. Weather factors today are the main ingredients in a recipe for elevated potential of natural avalanches. Warming temperatures and snow turning to rain will create a textbook red flag situation. However, south winds shifting southwest will reduce the amount of snow blown into our forecast area from the amount that we might see from a typical westerly. Expect 2-4” of snow transitioning to wet snow and sleet before turning to all rain near the end of the daylight hours. The current summit temperature is 15F (25F at 4300’) and will rise to and just above the freezing mark by mid-afternoon. Several small, human-triggered avalanches yesterday in the Lip and Sluice areas along with a couple of near-miss long sliding falls served as a reminder to the several dozen people around Tuckerman Ravine that the mountains operate according to their own calendar. Two wind slabs released above the ice crust, more than likely with some early faceting serving as the weak layer. A much thicker (16”), but fortunately small in area, slab broke off leaving a booting skier stranded in steep icy terrain without crampons over a small cliff with only a Whippet in hand.

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., Monday, April 11, 2016. A new advisory will be issued tomorrow.

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