Avalanche Advisory for Monday 12-16-2013

Expires at 12:00 midnight Monday 12/16/2013

Tuckerman Ravine has Considerable, Moderate and Low avalanche danger. Sluice, Lip, Center Bowl, Chute and Left Gully have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely in these areas. Hillman’s Highway has Moderate avalanche danger. Evaluate snow and terrain carefully in Hillman’s. Lobster Claw, Right Gully, Lower Snowfields and Little Headwall have Low avalanche danger due to limited snowcover. Continued wind loading will increase the likelihood of avalanches today.

Huntington Ravine has Considerable, Moderate and Low avalanche danger. Damnation, Yale, Central, and Pinnacle Gullies have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely in these Considerable rated areas. North and Odell have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. South Gully and Escape Hatch have Low avalanche danger. Continued wind loading will increase the likelihood of avalanches today.

AVALANCHE PROBLEM: Moderate to intense wind transport of yesterday’s 14” of light density snow will continue today. Windslab will continue to develop on our thin snowpack which consists of relatively weak, cold snow with areas of older, harder raincrust. Bed surfaces are limited in size in the lower rated areas and largest in the Considerable rated areas. Pockets of new snow also exist in locations sheltered from southerly winds during the December 14-15 snow event which could produce soft slab avalanches.

WEATHER: West winds blowing 60-80 mph will shift to the northwest and decrease slightly to 50-70 mph. These windspeeds will be very effective at picking up and moving snow into avalanche start zones on slopes and gullies with east and southeast facing components. Falling temperatures will slow the sintering and stabilizing process. Radar indicates continued snow squall activity as lingering moisture produces upslope snowfall. This new snow will contribute to windslab development and reduced visibility.

SNOWPACK: Easy and clean shears in new snow layers were observed in sheltered locations yesterday due to density/crystal form changes during the 14” snow event. This new snow is currently blowing into east and southeast facing forecast areas and forms the primary stability concern. Prior to the new snow, early faceting occurred in many areas. Though these facets probably will not be the weakest layer they may contribute to a weakening of overlying windslabs or sluff piles such as can be found at the bottom of the first pitch of Pinnacle and beneath the main ice bulge in Central Gully. As is typical of our region and forecast area, spatial variability makes continuous assessment and reassessment of both the snowpack you are on and the snow you are moving into a necessity. Though our snowpack is patchy and discontinuous in nature, it is more than capable of generating avalanches of a size capable of carrying a person into rocks and over ice cliffs. Exposed terrain continues to supply terrain traps capable of catching avalanche debris to a depth capable of burying a person. Reduced visibility due to blowing snow will make visual assessment of snow and terrain challenging.

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 0900 Monday 12-16-2013  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

2013-12-16