Avalanche Advisory for Friday, December 23, 2016

Huntington Ravine has MODERATE avalanche danger. All forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain features carefully to identify features of concern.

 Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. Sluice, The Lip, Center Bowl, and Chute have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Lobster Claw, Right Gully, Left Gully and Hillmans Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Lower Snowfields and Little Headwall are not rated due to a lack of snow.

AVALANCHE PROBLEM: Wind speed and direction today are favorable for building wind slabs as wind accesses recent snow in the alpine fetch zone. Our danger rating today straddles the line between Moderate and Considerable ratings due to a combination of factors. Though the likelihood of natural avalanches is bordering on unlikely in our Considerable rated terrain, I wouldn’t assume that a natural could not happen based on increasing wind speeds. Human-triggered avalanches are certainly possible in lots of our terrain so travel carefully, protect yourself when entering deeper or hollow sounding snow on climbs in Huntington. If skiing in Tuckerman’s, consider the icy bed surface and high consequence, early season terrain with lots of boulders, small cliffs and trees in your path. Careful assessment of new wind slab will be crucial for safe travel today.

WEATHER: The summit recorded around 3” of new snow in the past 24 hours with totals diminishing rapidly as you descend in elevation to around an inch at Pinkham Notch. Winds began yesterday morning on the lighter side (35-45 mph) from the SW then shifted west and slackened for a few hours. Light snow showers continued through the night as winds increased to the 50-60 mph range from the WNW. Wind today will shift slightly to the west at 50-70 mph with gusts to 80 mph and summit temperatures in the upper teens.

SNOWPACK: Low wind speeds during the early and heaviest period of snowfall yesterday sits on top of an icy melt/freeze crust from the rain on December 18th. This fast sliding surface will make self-arresting extremely difficult whether caused by a slip and fall or even a small avalanche sweeping you off your feet. Variable wind speeds and direction over the past 24 hours have built wind slabs which should be clearly identifiable even from a distance today as visibility improves. Wind slabs will grow in density today and may exist over a weaker layer of softer snow deposited during yesterday relatively low wind speeds. We will try to post pictures today if visibility improves as forecast.

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 so you can avoid the detour. Please be careful of construction debris near crossover 7 on the Sherburne Trail and watch out for machine traffic since the Tuckerman Ravine trail is still not really passable for snow machines. Thanks for your continued patience!

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 7:50 a.m., Friday, December 23, 2016. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2716

2016-12-23