Avalanche Advisory for Saturday, January 7, 2017

This advisory expires at Midnight tonight.

Huntington Ravine has MODERATE and LOW avalanche danger. Yale, Central, Odell, South and Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. North, Damnation and Pinnacle have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger. Sluice, Lip, Center Bowl, Chute and Hillmans Highway have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern. Lobster Claw, Right Gully and Left Gully have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. Lower Snowfields and Little Headwall are not rated due to a lack of snow but look for overhead hazard in Lower Snowfields which remains mostly tree covered except beneath Duchess.

AVALANCHE PROBLEM: Upslope snowfall from the past few days and wind deposited snow from Wednesday’s storm has lightly blown into gullies and covered the higher summits. There are currently two avalanche problems to be concern about. The most likely to occur in steep terrain are loose dry avalanches. Managing your sluff will be worth your time. The most consequential avalanche problem is the old wind slabs and buried crusts with facets scattered through the terrain. These slabs vary widely in thickness and strength and haven’t yet produced an avalanche but that possibility should remain on your radar. An avalanche that breaks on these facets could produce a larger and more dangerous avalanche than the more likely loose, dry sluff. If wind ramps up earlier in the day than forecast, look for developing wind slabs.

WEATHER: Multiple days of light accumulations of dry upslope snow have coated the higher terrain. Wind is calm at Hermit Lake this morning, with summit winds at 17mph from the west. A half an inch of snow was recorded in the past 24 hours at Harvard Cabin though snow which fell Wednesday and Thursday remains in the terrain due to low wind speeds over the past 36-48 hours. Cold temperatures have dried out the snow near the surface and created the right-side up surface snow,

SNOWPACK: Field work yesterday revealed a surprising amount of boot-top dry snow in Central Gully and Hillman’s Highway. This snow was deposited by low wind speeds but was sapped of energy by the drying effect of recent cold temperatures. The same cold temperatures that have dried out the upper snow has driven the faceting process that has created the facets around the buried crusts. This faceting around the crusts has us thinking about persistent slabs but terrain factors, spatial variability and previous avalanche cycles have kept this problem isolated. At lower elevations and more southern areas of the WMNF this crust is thick and brutal to travel over but the upper elevations escaped the bulk of rain from most recent storm on Wednesday. Crampons and snowshoes or skis are key equipment for a high traverse now.

The Lion Head Winter Route is open and the most direct route to the summit. The Tuckerman Ravine Trail bridge is completed enough to allow traffic again. Please be careful of construction debris near crossover 7 on the Sherburne Trail when skiing or riding.

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 7:55a.m., Saturday, January 7, 2017. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713

2017-01-07