Avalanche Advisory for Sunday, December 28, 2014

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. Sluice, Lip, Center Bowl Chute and  Left Gully have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack and weather evaluation, cautious route-finding and conservative decision making are essential.  All other forecast areas have Moderate avalanche hazard. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow, weather and terrain carefully.

Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger today. Yale, Central, Pinnacle, and Odell have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely.  Careful snowpack and weather evaluation, cautious route-finding and conservative decision making are essential. All other forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow, weather and terrain carefully.

AVALANCHE PROBLEM: Todays Wind Slab and Storm Slab problem is tied directly to wind speed and direction as well as total snowfall expected today. 2-4″ (5-10cm) of new snow is forecast and the current rate of precipitation at Pinkham and Hermit Lake is raising concerns that we may quickly reach the upper end of the forecast amount. The likelihood of natural avalanches will increase through the day as upslope snow showers accumulate and wind loading continues.

WEATHER:  Anticipate wind loading on east and southeast facing aspects as well as lee areas as wind shifts from the W to the NW at 60-80 mph (95-130kph). Lingering moisture will continue to generate upslope snow showers as the front passes which is creating our stability concerns as well as hamper visibility. Reduced visibility from fog and blowing snow may challenge your ability to assess the extent and size of potential wind and storm slabs. Though temperatures low on the mountain at this hour are allowing a copious drizzle to fall, anticipate temperatures to drop through the day to the lower teens F (-9 to -12C) tonight. Rain/snow line was at around 3700′ at 7:00am.

SNOWPACK: Our snowpack took a beating from recent warm temperatures and rainfall. Melt channels and signs of ice fall peppered the snow surface yesterday. Many areas are likely undermined and many frozen waterfalls are either detached or missing. Due to above average December snowfall, there remained ample bed surfaces in leeward slopes like Central Gully, Sluice, the Lip, Chute and Left. While certain factors  lead me to believe that we may not reach a Considerable rating, I wouldn’t bet my life on them. Warm incoming snow on a fairly coarse bed surface with abating winds may yield fair stability from a right side up slab configuration and reduce the likelihood of natural avalanches from possible to unlikely. Coupled with discontinuous bed surfaces in many areas like Center Bowl we may make it through the day without natural avalanche activity. Though our avalanche character may end up being on the small side, the nature of our terrain makes the outcome of an avalanche as dire as ever. The consequences of making the wrong stability assessment above rocky cliff bands and frozen waterfalls such as the Lip while on the Tuck trail, or anywhere in Yale or Pinnacle would be catastrophic. Other areas with larger potential bed surfaces like Central Gully or Chute will make the potential for a larger avalanche more likely and make the Considerable rating feel much more accurate if you find yourself in or below this terrain. Today is a day when you’ll want to use all of your strongest weather observation and snowpack evaluation skills if you venture into avalanche terrain.

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 8:20 a.m. December 28, 2014. A new advisory will be issued tomorrow.

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

2014-12-28 print friendly