Avalanche Advisory for Tuesday, March 1, 2016

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. Right Gully, the Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Left Gully and Hillman’s Highway have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features. The Lobster Claw, Lower Snowfields, and Little Headwall are not posted due to a lack of snow in these areas.

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

AVALANCHE PROBLEM: Wind slab is the primary avalanche problem today. The greatest likelihood of unstable snow will be found in the most strongly sheltered lee areas such as the Lip and Center Bowl. In many other areas regardless of the dominant aspect, you may find smaller terrain features with new wind slabs. In Huntington, be cautious on the approaches to climbs such as Pinnacle and Odell; sluff piles at the base of ice are a potential location for avalanches to be triggered today.

 WEATHER: Today’s avalanche problem is being driven by yesterday’s weather. The upper mountain received over 6″ of snow in the last 24 hours. At Hermit Lake and possibly above, light rain fell for a short time in the afternoon. Of particular importance, a line of snow squalls came through overnight, bringing a quick blast of heavy snow along with thunder and lightning. Winds were very strong at this point. Several hourly observations at the summit showed winds blowing over 90mph (145kph). Westerly winds will be starting strong today but diminishing consistently until dusk.

After dark we should start to see the first precipitation from an incoming winter storm. The latest information shows it bringing mostly snow to Mt. Washington, with some mixed precipitation likely. Total water equivalents might range from 0.5″ to 1.4.” Winds on Wednesday will be increasing throughout the day. I’d strongly encourage you to read tomorrow’s avalanche advisory before committing to a plan in either ravine.

 SNOWPACK: With just a dusting of snow barely concealing the ice on the lower part of the mountain, I was pleasantly surprised to see Tuckerman this morning with areas of smooth, freshly loaded wind slab. The Lip, Center Bowl, and Chute have the greatest potential for holding unstable slabs. Certainly some areas got pummeled by the strong winds in the overnight hours. Areas of Huntington, Left Gully, and Hillman’s are examples of locations that tend to get hammered into good stability during strong winds. These locations will have a more textured appearance and will be firmer underfoot, but may have smaller sheltered pockets where you could find unstable slab. Be increasingly cautious anywhere you find hollow slabs with soft snow underneath.

The overnight snowfall is an interesting one. If your read the 6+” amount above and got all excited about powder, please allow me to temper your enthusiasm with a dose of reality. At Hermit Lake our snow totals were knocked down by some rain in the afternoon, and the overnight snow only left small amounts on the ground here. With winds currently blowing 75mph (120kph), there is very little active loading taking place. This tells me that there isn’t likely 6″ of new snow sitting in elevations below the ravine tops. It seems as though the greatest snow totals were found only in the uppermost elevations.

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 9:00am, March 1, 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