Avalanche Advisory for Friday, January 6, 2017

This advisory expires at Midnight tonight.

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. Evaluate snow and terrain carefully. North, Damnation and Yale have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

 Tuckerman Ravine has MODERATE and LOW avalanche danger. Sluice, Lip, Center Bowl, Chute, Left Gully and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Lobster Claw and Right Gully have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features. Lower Snowfields and Little Headwall are not rated due to a lack of snow coverage. Some open water remains in the drainage above and in the Little Headwall. Sluff piles are growing in Duchess but lot of trees remain below.

AVALANCHE PROBLEM: Our danger rating remains the same from yesterday due to the neutral, or possibly downward, trend in snow stability. Recent cold temperatures have advanced the development of facets around two existing buried crusts. Smaller, softer surface wind slabs are the primary concern today. These would be capable of producing a small to medium sized avalanche. The next concern would be deeper, older hard slabs releasing on the more deeply buried melt/freeze crust. This layer is on the cusp of becoming a persistent slab. So far the slabs have been resistant to human-triggering with limited recent traffic but has shown a tendency to propagate in an area low in Chute but not over low in the Lip. The possibility is there to find the “right” thin spot for triggering so apply your terrain management and snowpack evaluation skills when moving around in the terrain.

WEATHER:  The summit recorded a half inch of snow in the past 24 hours with diminishing west winds from the 70 mph range down to the mid-so mph range where they stand at this hour. Temperature has hovered between -6 and -2F during this period as well. Snow flurries and some summit fog are currently challenging visibility but should begin slowly clearing later this morning. Wind will shift a bit to the northwest and diminish further with a high temperature of 0F today. Temps will remain cold through Saturday but fortunately wind speeds are forecast to be in a reasonable range for the well prepared.

SNOWPACK: Compression tests yesterday revealed an easy (from the wrist) shear in the uppermost layer, but as we often find in our variable thickness wind slabs, the quality of the shear was variable. Deeper down, the weak interface was moderate (from the elbow). These layers showed a tendency to propagate a crack in one location yesterday and with cold temperatures today and through the weekend these facets may grow and spread. There are a lot of terrain factors that allow these firm slabs to bridge and remain in place but slight convexities, unsupported pockets or the right weak spot, perhaps with some buried, pooled graupel (heavily rimed snow particles) could become the villain that lights the fuse. Though the likelihood of triggering one of these buried slabs could be considered unlikely, it remains enough in the realm of possibility to keep our danger rating elevated.

The Lion Head Winter Route is open and the most direct route to the summit. Please be careful of construction debris near crossover 7 on the Sherburne Trail when skiing or riding.

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 8:00a.m., Friday, January 6, 2017. A new advisory will be issued tomorrow.

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

2017-01-06