Avalanche Advisory for Friday, January 29, 2016

All forecast areas of Tuckerman Ravine have LOW avalanche danger.  Natural and human triggered avalanches are unlikely.  Watch for unstable snow in isolated areas.  Lobster Claw, Lower Snowfields, and the Little Headwall are not posted due to lack of snow cover. Exercise caution in these areas.

Huntington Ravine is under a General Avalanche Bulletin which is issued when instabilities are isolated within forecast areas and are re-issued every three days, or earlier if conditions warrant. These areas have less well-developed snowfields to produce avalanches than Tuckerman, but understand instabilities in these smaller locations may exist.  Some of these can be found at the base of Central, Pinnacle and scattered through Odell and South gullies. The North, Damnation, and Yale gullies have good ice growing, but hold very little snow. It is critical that you assess snow and avalanche conditions if venturing into Huntington to determine any localized snow instabilities.

AVALANCHE PROBLEM: A couple inches (5cm) of new snow on light to moderate winds through daylight hours may create spindrifts or Dry loose avalanches and small Wind slabs. The forecasted shifting wind in the 20-30 mph (32-48kph) range around mid-day may crossload a lot of areas rather than build large slabs in relatively few areas. Sadly, we still have what amounts to an early season snowpack with generally small snowfields for recreation. The new snow may also feel like a dust on crust scenario with the underlying firm snow being the primary travel surface. Expect a breakable old wind crust over facets when traveling around rocks and bushes and the potential for long sliding falls on steeper slopes. Check back tomorrow morning for updated snowfall totals as they are likely to create new wind slab problems.

WEATHER: Scattered snow showers are forecasted into Sunday morning with a trace to 2″ (5cm) expected each 12 hour period.  This could add up to a handful of inches by the end of the weekend.  Today, showers are anticipated mainly in the afternoon on a shifting and increasing wind moving from the S, through the W, eventually to the NW late.  Velocities will begin rather light, blowing around 15 mph (24kph), and build towards 50mph (80kph) in the alpine zone by late in the day. As of this morning we are just a few degrees away from the expected high of 20F (-6.5 C).  Temperatures will fall overnight and recover slowly tomorrow while winds grow and shift back to the W. Gusts on Saturday night may exceed 80mph (128kph).

SNOWPACK: Our snowpack consists of  very strong, old wind slabs and while some weak layers exists beneath, it will take considerably more loading than we are likely to see today to overload these layers. Firm slabs (P hardness) have dominated the surface in our terrain for many days now. This surface slab varies in thickness but is very strong in the areas where there is enough continuous snow to be appealing for climbing or skiing. The firm snow is just barely bootable, and edge-able, but the extra security of crampons is a good idea when slopes steepen or when climbing above boulders or cliffs. Needless to say, missing a turn in many areas could result in a long ride on a fast surface. The layer of facets that exists between the basal ice crust from our rain on snow event weeks ago and the old wind slabs is worth looking at and keeping in the back of your mind for the future.

The Lion Head Winter Route is open and is recommended for those opting to avoid avalanche terrain in the early season. Microspikes and ski poles are helpful on lower elevation trails, but are not substitutes for crampons and an ice axe on this route. The John Sherburne Ski Trail is passable but has become harder with expanding water ice each day. This issue can be added to many waterbars and occasional rocks. Expect very challenging conditions, particularly if a thin veil of new snow hides these landmines over the weekend.

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 8:00 a.m. January 28, 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

2016-01-29