Avalanche Advisory for Tuesday, February 9, 2016

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 and identify features of concern. Lobster Claw, Lower Snowfields, and the Little Headwall are not posted due to lack of snow cover. Exercise caution in these areas.

AVALANCHE PROBLEM: Today there will be two primary avalanche problems competing for your attention, the establishment favorite wind slab, and the outsider candidate, loose dry avalanches. Dust on crust is an apt description of the current situation, with soft slabs expected to become a problem. The extent will be dependent on how much new snow the winds are able to transport into the ravines. Expect the slabs to be softer than usual for Mt. Washington. Any location where you find snow deeper than a few inches should raise a red flag in your mind. Previous to new snow, there were only a few older windslabs in strongly sheltered areas (such as the Lip) that harbored potential instabilities.

Loose dry avalanches may also be a threat, particularly in gullies where the terrain funnels snow into deeper, heavier masses of moving debris. Climbing routes in Huntington are prone to this problem being worse than more open snowfields found elsewhere.

WEATHER: A light, long-duration snowfall began yesterday afternoon and is tapering off this morning. So far, we have recorded 2.5” (6.5cm) of new low density (7.5%) snow at Hermit Lake. The summit is recording slightly more snow (3.7” or 9cm) with a very low density (2.5%). As snowfall began, winds were from the E around 30-40mph. They flipped to the W overnight and simultaneously dropped to single digit speeds. Today, we are expecting a modest increase in wind velocities coming from the NW. Additional snowfall today will be limited, with a trace to 2” possible.

SNOWPACK: For the most part, today’s problems are a result of the recent snow and expected increase in winds. Low density snow can easily be moved by light winds, so when winds reach into the 20-30mph range, you should be watchful for the development of new soft slab. These will likely be very soft, but will be cohesive enough to fracture as a slab. I don’t expect very large or destructive avalanches, but simply being knocked off your feet on the previously existing ice crust can be a harrowing experience.

Today is the first day we are putting a rating to the northern gullies in Huntington. This is due to the potential for loose dry avalanches as well as the potential for growth of soft slabs in the upper avalanche start zones. When the current active weather pattern changes, we may return to a “no rating” for these areas. But in the meantime, we want you to be aware that avalanche hazard may exist in these areas.

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 9, 2016. 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