Avalanche Advisory for Sunday, December 11, 2016

This advisory expires at Midnight tonight.

Huntington Ravine has MODERATE and LOW avalanche danger. Central, Pinnacle, and Odell Gullies have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain features carefully. North, Damnation, Yale and South have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. Escape Hatch is not rated due to a lack of snow.

Tuckerman Ravine has MODERATE and LOW avalanche danger. The Lip, Center Bowl, and Chute 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. Right Gully, Sluice, Left Gully and Hillmans Highway have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. Lobster Claw, Little Headwall and Lower Snowfields are not rated due to lack of snow.

AVALANCHE PROBLEM: Currently, firm Wind Slab is the predominant avalanche problem in our terrain. The thickness of this slab varies greatly across the terrain and even within each gully or forecast zone. These firm slabs may be resting on top of softer snow in places. Where these slabs are thick (3’ or more) they are likely to be very stubborn and resist triggering. Where they are thinner, they become more easily triggered by your weight. Smaller and softer slabs built after the high winds Friday evening are also around the terrain in sheltered, lee pockets. These are smaller in size and distribution but could still cause problems if triggered.

WEATHER: Cold temperatures yesterday and last night did little to aid in the settlement of the snowpack. Strong winds early yesterday scoured a lot of terrain and packed snow into the previously mentioned firm slabs. Today will be the proverbial calm before the storm as a brief spell of high pressure allows for some clearing of summit fog. Temperatures will remain around 0F before rising into the teens later in the day and this evening. West winds 40-55 mph will slacken to the 25-40 mph range. Winds are calm in Pinkham Notch.  Anticipate elevated avalanche danger tomorrow due to 12 of new snow forecast for the higher summits.

SNOWPACK: You’ll find several surfaces to travel on in our terrain today. Heavily scoured areas consist of a refrozen crust of wet snow and rain from the late November thaw. Above this on areas not scoured by wind or avalanche activity, soft weak layers contain a mix of rimed particles and other fist hardness fragmented grains beneath the previously mentioned wind slabs. Lots of rocks, cliffs and bushes remain above or just beneath the surface. The Open Book and other features in the Lip and Center Bowl area remain unburied by blown in snow or avalanche debris.

The Lion Head summer trail remains the better route to the summit from the east. We are keeping tabs on the development of the avalanche paths that threaten that trail and will switch to the using the winter route as snow continues to fill things in. Remember that the bridge work continues on the Tucks Trail so use the detour on the Huntington Ravine trail. Some folks may opt to skin up the Sherburne ski trail so be on the lookout for them and for machinery when skiing or riding. The lower half of the Sherburne will be generally hard today with broken up ice from machine traffic and soft but very thin snow on the edges.

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., Sunday, December 11, 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

2016-12-11