Avalanche Advisory for Wednesday, January 20, 2016

All forecast areas of Tuckerman Ravine have MODERATE avalanche danger. Heightened avalanche conditions exist on specific terrain features.  Natural avalanches are unlikely and human-triggered avalanches are possible. Lobster Claw, Lower Snowfields, and the Little Headwall are not posted due to lack of snow cover. Exercise caution in these areas.

Huntington Ravine is under a General Avalanche Bulletin. General Bulletins are issued when instabilities are isolated within forecast areas and are issued every three days or earlier if conditions warrant. Forecast areas in Huntington have less well-developed snowfields to produce avalanches. How the recent strong winds have affected snow coverage in Huntington remains to be seen. It is critical that you assess snow and avalanche conditions if venturing into Huntington.

AVALANCHE PROBLEM: If we could see into the ravines this morning, what we expect we’d see is a lot of hard wind slabs left over from the wind loading that has been taking place over the last couple days. Wind slabs are your primary avalanche problem. The size and extent of the problem will depend largely on what slopes have avalanched recently and when, which we are unable to determine as of yet due to the thick fog. The existing slabs will likely be strong and stubborn to human impacts, but if you should find the sweet spot and trigger an avalanche today, it will be in an unforgiving layer of dense hard slab. As long as winds are able to find snow to transport into the ravine, we cannot rule out the potential for a naturally triggered avalanche today. Areas such as the Lip, Center Bowl, and Chute are at the upper end of the Moderate rating.

WEATHER: It’s been a wild couple days up here weather-wise. Yesterday’s peak gust didn’t get as strong as forecast, but 117mph (190kph) isn’t bad. Persistent snowfall on Monday brought roughly 5” (7.5cm) of new snow to the summit, which has been followed by the fog and very strong westerly winds. These winds have kept blowing snow in the hourly observations at the summit for more than 48 hours straight. Today you’ll face persistent strong winds, cold temperatures, and some additional blowing snow. These are certainly are “full winter conditions.” Thankfully, we are trending toward clearing conditions which will hopefully provide some visibility this afternoon.

SNOWPACK: As mentioned, we have been unable to get even visual observations of what’s happened in the last couple days here, so we don’t have first-hand data regarding the snowpack. Looking at the weather for the last few days and the forecast, we believe we may still have wind loading taking place today as a slow shift in wind direction from the W to the NW may access snow that had settled into small lee features in the alpine zone. Surface slabs are often quite strong after this type of event, especially in areas where it is thickest. However, due to the lean coverage this year we have a lot of places where the slab may be thin enough for you to impact a weak layer, such as edges (where slabs tend to naturally become thinner) and near buried rocks or trees. Your ability to navigate the proverbial minefield will be an important factor in keeping safe. Additionally, the currently disjointed nature of our terrain can allow for some very sheltered location to harbor some softer slabs.

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 8:30 a.m., Wednesday, January 20, 2016. A new advisory will be issued tomorrow

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856