Avalanche Advisory for Sunday, December 25, 2016

This advisory expires at Midnight tonight.

Huntington Ravine has MODERATE and LOW avalanche danger. Central, Pinnacle, Odell and South have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. North, Damnation, Yale, and Escape Hatch have Low avalanche danger, Natural and human-triggered avalanches are unlikely. Evaluate snow and terrain features carefully.

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

AVALANCHE PROBLEM: In the past 24 hours, 2.3” of new snow fell with increasing wind speeds that created wind slabs in our forecast areas. Most of this snow fell in the morning through mid-day hours yesterday and was followed by strong WNW winds which loaded this snow into lee areas. These wind slabs are generally stiff and strong and therefore stubborn but weaker layers exist above the old icy crust. The greatest concern for a human-triggered avalanche is in the Lip and Center Bowl area of Tuckerman Ravine and in Central Gully in Huntington. Smaller but still potentially consequential pockets exist in many other areas so travel carefully and protect yourself before climbing into these pockets or avoid them altogether by staying on the old crust.

WEATHER: Temperatures in the teen’s this morning will fall further into the single digits as winds ramp up into the 70-90 mph range this afternoon. Wind will shift from west to north with gusts to 115 mph possible on the summit. Snow continues to be blown around as scouring and wind-packing of snow particles continues. Today would be good day to try out the new googles and balaclava Santa brought you, though staying home and roasting chestnuts by an open fire sounds even better.

SNOWPACK: Wind slabs which developed Thursday and Friday were unreactive Friday. Warm temperatures (38F at Hermit Lake) yesterday morning helped snow to settle further. The surface wind slab built yesterday was variable in thickness and tough enough to resist sustaining a crack for any great distance. That said, a weak layer of rimed snow from Friday created planar shears yesterday afternoon. The fact that the wind slabs are widely scattered through disconnected slopes is keeping our avalanche danger down. Plenty of old surface is still providing safe travel options to avoid suspect areas. This refrozen crust is hard enough to warrant crampons as terrain steepens but is breakable over faceted snow off trail so expect post-holing conditions in less frequently travelled terrain.

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 7:55 a.m., Sunday, December 25, 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