Avalanche Advisory for Wednesday, February 11, 2014

This advisory expires tonight at 12:00 midnight.

All forecast areas of Tuckerman and Huntington Ravines have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully. Natural avalanches are unlikely and human triggered avalanches are possible. The only exceptions to this are the Lower Snowfields and Little Headwall in Tuckerman, which have Low avalanche danger. Natural and human triggered avalanches are unlikely in these areas except for small avalanches in isolated terrain features.

AVALANCHE PROBLEM: With weather not being much of a factor to increase or decrease the avalanche danger, today is a “what you see is what you get” type of day. Wind slabs are the dominant problem and should raise the hairs on the back of your neck in many areas. In Huntington, as well as Hillman’s and Left Gully in Tuckerman, you might find routes to climb up through with reasonable stability. However, you’ll need to carefully assess the snowpack if you plan to descend on skis or boards. Areas that were in the strong lee of NW winds, such as the Center Bowl, Lip, and Sluice in Tuckerman have widespread areas of new slab and are leading the list of problem areas. Back to Huntington, areas above and below the ice in Central and Odell are the most concerning, but all locations have snow somewhere that warrants the Moderate danger rating.

WEATHER: The storm Saturday night through Monday left about 8” of low density snow after settlement is accounted for. This fell with very light winds, but yesterday velocities ramped up for several hours in the afternoon, reaching a peak gust of 60mph (96kph) on the summit. This morning is gloriously sunny with relatively calm air again. Temperatures are currently a seasonable 12F (-11C) at Hermit Lake at 7:30. Slopes with a southerly exposure may see some solar gain before clouds begin to arrive later today.

SNOWPACK: Today’s avalanche problem was created yesterday in the late afternoon. Due to the timing of the wind increase, we have not yet had our hands in the snow to see how this snowpack has developed. However, you don’t need to be Sherlock Holmes to put together the pieces of what has likely happened. Picture the entire mountain covered in several inches of weak unconsolidated snow. On S- and SE-facing slopes, the snow gained some cohesiveness during the morning sunshine. We saw a small slab release in the lower Lip area around 11am, as well roller balls of snow and loose point releases elsewhere. We also learned of an inconsequential skier-triggered soft slab in the Gulf of Slides. Around 12noon, we started to see snow blowing around above the ravines. This is when the loading and slab development began, and it continued for about 6 hours before winds subsided again. We are now left with wind slabs over weak snow in many areas. These will vary in their degrees of instability. Some locations deserve the “scary Moderate” moniker (e.g. the Lip and Center Bowl) while other locations may be navigable by experienced travelers who are competent with their terrain management and snowpack assessment skills.

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 8:15 a.m. February 11, 2015. 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

2015-02-11