Avalanche Advisory for Sunday April 12th, 2015

This advisory expires at Midnight.

All forecast areas of Tuckerman Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features. Unstable snow may exist on isolated terrain features.

A General Advisory is currently issued for Huntington Ravine. We have stopped issuing daily avalanche forecasts for Huntington for the remainder of the season. You will need to do your own stability assessments when travelling through avalanche terrain. A danger of falling ice will begin to increase, along with other spring hazards, with the seasonal warm up.  These hazards will persist until melt-out as we transition into early summer.

AVALANCHE PROBLEM: Rain and warm temperatures induced intense melting and free water percolation deep into the upper snowpack on Friday.  This was followed by high winds and a cold front Friday night and Saturday, beginning the refreezing process from the surface down.  The resulting lock up has dramatically reduced the avalanche problem and hazard.  As temperatures increase today and winds fall, anticipate the potential for skier induced Wet Loose sluffing to occur.  This is particularly true in locations that have not seen any traffic or sluffing already and appear to be the most desirable steep S or SE facing slopes.  The greatest associated hazard with wet sluffing today will be the potential of entrainment and being dragged over things that you weren’t planning on like rocks or cliff bands.  If temperatures warm up significantly and penetrate deep, melting bonds in the upper snowpack, a sizable wet sluff has the remote potential to trigger a wet slab.  This is generally unlikely, but worth considering depending how the afternoon temperatures develop.

WEATHER: Temperatures have been holding rock steady in the mid teens F since yesterday.  The mercury will rise today, likely to break the freezing mark even on the higher summits.  Winds will fall from their current of 65mph (kph) to as low as 35mph (kph) from the NW under mostly sunny skies.  For those prepared it should be a fairly pleasant day to be in the mountains.

SNOWPACK: Surface snow took a beating on Friday due rain settlement channels and chunky wet sluff debris. Making turns across some of these runnels or wet debris will be challenging until things warm up significantly.  Expect today to be one of those classic mornings where waiting for a slight warm up and then getting onto S facing slopes to be way more enjoyable than running onto slopes facing toward the NE first thing this morning.  As mention above, think about skier induced sluffing in the near surface snow as connecting bonds melt into the afternoon.  This can be managed by using good sluff tactics allowing moving snow to go by giving it a wide berth.  If you are someone below a skier entering untouched snow consider this potential.  This probability will not be a widespread issue, but something to consider as the day warms up.  A more distant issue could be a wet sluff impacting a slope below inducing a wet slab to fail. This would likely need to be a sizable sluff coming over a cliff band to provide enough impact so this is fairly remote, but not impossible very late in the day.

OTHER HAZARDS:  The greatest hazard this morning and again very late in the day will be long sliding falls on the icy, refrozen snow. Ice axe and crampons are highly recommended for travel on angled terrain anywhere beyond mellow hiking trails. Microspikes or other traction devices along with ski poles are helpful to hike up from Pinkham to the base of the Ravines.  However they are NOT crampons and do not replace them, an ax and the skill to self-arrest in steeper terrain. We are seeing an increasing number of accidents in recent years because of people misunderstanding the limits of Microspikes.  Serious accidents and fatalities have resulted from this misperception.

The Lion Head Winter route remains the recommended east side route to the summit. It requires mountaineering skills and experience.  Skiing from the Ravine down the Sherburne ski trail to the parking lot is still possible.

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 8:10.m. Sunday, April 12, 2015. A new advisory will be issued tomorrow.

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

2015-4-12