Avalanche Advisory for Thursday, March 10, 2016

All forecast areas of Tuckerman Ravine have CONSIDERABLE danger. Dangerous avalanche conditions exist. Natural avalanches are possible and human-triggered avalanches are likely. Lobster Claw, the Lower Snowfields, and Little Headwall are not posted due to a lack of snow in these areas.

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

AVALANCHE PROBLEM: Wet slabs and persistent slabs are the avalanche problems today. Continued warm temperatures will reach deeper into the snowpack and further destabilize slopes. Rain may also add weight and further weaken the already stressed weak layers in the snowpack. Consider the small natural avalanche in Center Bowl yesterday as confirmation of red flags created by a warming trend. A layer of weak, sugary facets had not yet been reached by warming temperatures yesterday. Today’s warmth and rain might awaken a larger avalanche dragon.

WEATHER: Unpleasant but warm weather and gloppy, wet snow will greet those heading into the mountains today. The likelihood of rain showers will increase through the morning hours with steadier rain developing in the afternoon. Expect snow stability to be at its poorest later today as rain and warm temperatures reach deeper into the snowpack.  Temperatures today in the mid-40’s F will not drop until the early morning hours tomorrow, bringing a stabilizing trend. Below freezing temperatures tomorrow will hopefully set the stage for a corn snow cycle this weekend.

SNOWPACK: Wind slabs on the surface from new snow over the past week or so (8” last Wednesday, 2” on Monday) were failing in the moderate to hard range (CT 18-21, down 40-45cm) yesterday in a safe spot on a 30 degree slope in the Lower Snowfields. In this location, the surface slab did not show a tendency to propagate into a larger avalanche due to the low cohesion of the moist snow. However, propagation saw tests run through the fist hardness facets beneath the thin ice crust from Feb 2nd rain were showing reactivity (PST 20/100 End, down 45cm). It is this deeper layer that is the spookiest feature in my mind in our snowpack. This layer exists at various depths and locations in many areas of the terrain and often less than 1m down, well within the reach of the impact of a person on foot or ski. This weak layer has been shielded and bridged over by a firm slab and melt freeze crust that are weakening as heat reaches into the snowpack. The lower third of the Sherburne Ski Trail is grim with long stretches of ice producing better turns that nearby grass patches that are emerging. Upper Sherburne is wet, grabby and slow. Expect to posthole here and there through the weakening packed snow surface.

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 7:10a.m., Thursday, March 10, 2016. 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