Avalanche Advisory for Saturday, February 13, 2016

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. The Lip, Center Bowl, and Chute have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack evaluation, cautious route finding and conservative decision making are essential. Right Gully, the Sluice, Left Gully and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern. Lobster Claw, Lower Snowfields, and the Little Headwall are not posted due to lack of snow cover.

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. North, Damnation and Yale have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Exercise caution in these areas and expect the potential for isolated patches of instability.

AVALANCHE PROBLEM: Wind slab is the primary avalanche problem today. New wind slabs will develop as winds blow new snow falling this morning over existing wind slabs this afternoon. A fairly large avalanche from the mid-elevation start zone of Center Bowl on Thursday night left plenty of hangfire. The Chute also avalanched above the choke but left plenty of slab remaining on the right side with the bed surface reloading yesterday as well as today. The Sluice forecast area did not avalanche and, along with the Lip, will directly threaten the floor of Tuckerman, Lunch Rocks as well as the Tuckerman Ravine summer trail today. Anticipate avalanche danger to rise to its forecast rating this afternoon as wind speeds ramp up.

WEATHER: Temperatures will drop to the lowest levels of the season tonight.  Mercury falling to -35F, coupled with hurricane force winds on the summits, will even make the granite boulders shiver.  Depending on the exact path of the low pressure, temperatures may be a bit warmer or colder during the overnight before rebounding quite a bit tomorrow.  However, the biggest current concern affecting snow stability is this morning’s brief, but potentially intense, snowfall delivering up to a quick 2″ on a mild WNW wind. Velocities will pick up this afternoon and by 3, 4, and 5 o’clock winds gusting to 65+ will transport the morning’s new snow into the Ravines.

SNOWPACK:  Moderately hard wind slabs are perched in lee areas throughout both Ravines due to the wind loading that occurred on Thursday. These firm slabs rest on a weak layer of lower density (F to 4F) snow. Softer pillows of slab are also in play in the most sheltered spots like lower Sluice, the Lip and Center Bowl. You’ll find harder slabs and even areas scoured down to the February 3rd-4th melt-freeze crust as well in both Ravines. The reduced visibility today due to light snowfall and summit fog will make it challenging to assess the surface snow conditions and identify hazards. In the steeper, sheltered terrain, these slabs will be more sensitive to triggering. Beware of the potential for folks unfamiliar with the terrain descending into unstable slabs and triggering an avalanche onto those below. The Tuckerman Ravine trail down into the Ravine would be the last route I would choose to escape high wind and cold temperatures on the summit today.

OTHER HAZARDS: Temperatures that will fall through the day, reaching about -35F tonight, should go into today’s decision making and trip planning.  Conservative turnaround times, short climbs, keeping a close eye on partners, and avoiding slow climbing would all be considered some prudent choices today.  The key is avoiding the potential for becoming benighted.  Having a timeline that gives you some extra margin to avoid being caught out after dark would be very smart.  Of course top quality boots, mittens, and head/face gear is critical and usually where we see people skimp in arctic conditions. Tonight, a hot tub and a beverage will be much nicer than a rock cave on Mount Washington.

The Lion Head Winter Route is open and the recommended east-side route to the summit that avoids avalanche terrain. The John Sherburne Ski Trail is skiable with most rocks and water ice covered by recent snow.

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 7:58 a.m. February 13, 2016. A new advisory will be issued tomorrow.

Frank Carus/Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856