Avalanche Advisory for Wednesday, March 30th, 2016.

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible.  Heightened avalanche conditions exist on specific terrain features.  Evaluate snow and terrain carefully to identify these features of concern.

Huntington Ravine has Low avalanche danger. Natural and human triggered avalanches are unlikely.

AVALANCHE PROBLEM: Hard Wind Slab is the avalanche problem today.  A period of snow, resulting in modest accumulations, ended about 28 hours ago culminating in very high winds gusting over 130mph (+208kph).  You can expect most areas to be scoured of new snow resulting in a patchwork of hard slab that survived in the strongest lee areas of W and WNW winds. Anticipate variable surfaces and stability based on your location.  Expect the easiest trigger point of hard slab to be on the outside edges where the depth is typically thinnest as well as shallow mid-slope spots that can be very hard to identify. Worldwide, these locations are classic triggering spots that users miss in their evaluations when skiing and riding.

WEATHER: On Monday the mountain received over 3/4″ of rain followed by 3.8″ of snow, which ended very early yesterday morning.  Winds raged between 90-133 mph for about 10 hours during the tail end of precipitation and in the hours following. Winds dropped through Tuesday, but blowing snow continued until the supply was exhausted after dark, even though winds remained over hurricane force.  Over the past 12 hours winds have fallen with high visibility from alpine terrain reaching 130 miles out.  Today, skies will be mostly clear with some building clouds, foreshadowing the approaching rain during the overnight, as spring temperatures and conditions return once again.  The mercury with climb today and eventually make it over the freezing point tonight, climbing to about 40F on the summits tomorrow, with….yup…. rain.

SNOWPACK: The quality soaking we received on Monday, with over 0.75″ of rain on the summit of Washington, gave us yet another factor to stabilize the mountain snowpack. We had a number of concerns prior to last weekend that were eventually reduced by Friday’s rain, warm conditions and skier compaction over the weekend, followed by more rain on Monday.  This stabilized the snowpack prior to new concerns that developed from the 3.8″ of snow falling from Monday night into very early Tuesday morning.  Currently, snowpack concerns remain solely from this new snow and not beneath the refrozen layers created by the warm up and rain from Friday to Monday.  Although limited in spatial distribution, assure you approach new slab with some respect and caution.  Skiers and riders may be tempted to seek out new snow but do so with conservative skepticism. These locales will most likely exist in the most protected areas below terrain features.  Examples include the roll over stretching from the Lip, through the left headwall, and including the Chute as you look up towards the south side of the ravine.  Besides avalanches, other spring hazards will come and go based on temperature and daily issues.  I would expect long sliding falls to be one of the main issues today with an increased threat of falling ice tomorrow with warm rain. These are the main factors to consider that historically have caused some tragic outcomes:    

  • Crevasses, moats and waterfall holes – Water flowing under the snow pack creates holes and thin spots in surface snow that are deep enough to injure or ….worse.
  • Long sliding falls are a significant threat today.Crampons, not Microspikes, are needed in most steep terrain. Arresting a fall on an icy steep slopes is practically impossible.
  • Falling Ice. Lunch Rocks and the floor are in the bullseye. Lunch Rocks, or “ICEFALL ROCKS”, gets hammered by ice every season it is not a good place to hang out. This location for many serious injuries over the years.

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 7:55 a.m., Wednesday, March 30, 2016. A new advisory will be issued tomorrow.

Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2716

2016-03-30