This advisory expires at midnight.
Huntington and 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. Dangerous avalanche conditions exist.
AVALANCHE PROBLEM: The current avalanche problem is the developing Wind Slab. New snow, wind, and a good bed surface are key ingredients for this problem and all exist this morning. Strong east winds are cross-loading many slopes, particularly the start zones of Pinnacle through Escape Hatch in Huntington and Left Gully and Hillman’s Highway in Tuckerman. Be aware that in our terrain, lower angled slopes often have several start zones above. Depending on what the weather does today, we may see these wind slabs become saturated with rain, turning into Wet Slab. With such a degree of uncertainty in the weather forecast today, it is imperative to keep an eye on the ground and to the sky, continually evaluating the snowpack.
WEATHER: Yesterday started with clear skies and calm NW winds. Through the day, winds shifted to the E and picked up in intensity while clouds slowly built. Snow began around midnight with steady E 60mph winds. Temperatures bottomed out at 12F and are rising with a current temperature of 20 on the Summit. Expect temperatures to continue rising, possibly reaching the 30sF during the day. Current E 80mph winds should decrease gradually through the day. Precipitation will fall all day; as to what form it will take up is in the air. Most scenarios are showing snow for the morning, transitioning to sleet and freezing rain midday with possible rain, and then returning to snow at the end of the day. Tonight, temperatures will move into the 20sF, winds will shift to the NW and increase, and snow/sleet will continue.
SNOWPACK: Warmer temperatures from January 20 through the morning of January 23 allowed the top ~30cm of our snowpack to develop a melt freeze layer. Snow below remained cold and dry. Conditions yesterday allowed a thin crust to form, but not one supportive to body weight. Three inches of snow fell overnight. Strong east winds are transporting this snow and cross-loading slopes with a northern and southern aspects. With rising temperatures, precipitation will become denser. Wet snow and maybe freezing rain falling on top of this slab will further the idea of an upside-down snowpack, possibly creating wet slabs. Whiteout conditions through the day will make tough visibility, a key component of traveling safe on a day like today. Winds shifting to the NW tonight may further load slopes, especially those with an easterly or southern aspect. Dangerous avalanche conditions exist today. Constant evaluation of what the weather is actually doing combined with keeping your hands in the snow will help make good decisions on a day like today.
The Lion Head Winter Route is open and the most direct route to the summit from the east side of the mountain. Please be on the lookout for machine traffic on the Sherburne.
- 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 8:15a.m., Tuesday, January 24, 2017. A new advisory will be issued tomorrow.
Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713