Avalanche Advisory for Thursday, April 3, 2014

Tuckerman and Huntington Ravines have LOW avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features.

Though heating of the snowpack is not likely today, expect avalanche danger to increase if temperatures rise significantly or more direct sunlight hits south facing slopes than is forecast.

AVALANCHE PROBLEMS: Currently the temperature on the summit is 10F and has remained well below freezing all night. This cold air has refrozen our snowpack and strengthened surface layers. Weak layers below will be much more difficult to trigger as a result, but Persistent Slabs will remain our number one avalanche problem today.

WEATHER:  Cold air will only warm from 10F to about 18F on the summit today. NW winds from 45-60 mph will decrease this afternoon.  Overcast skies will return later today with a chance of snow showers.

SNOWPACK:   Snowpack stability is currently at the whim of temperatures and melt freeze cycles.  Yesterday a number of areas were at a Moderate rating due to warm conditions penetrating into the snowpack. A number of locations became wet at the surface, particularly those with a S aspect.  Since the summit high of 31F (-1C) on Wednesday the mercury has fallen sharply to a current of 10F with winds from at the WNW at 45mph (73 kph).  This hard freeze has locked up freewater close to the surface and is working deep to chase any liquid water on S facing protected locales like Right Gully that warmed more than others.  This has created a hard yet porous crust that has strengthened the upper snowpack creating a bridge, or thick eggshell, over the deeper persistent issues we have been discussing.  Today temperatures are anticipated to rise, but only into the upper teens.  The overcast skies for a while this morning, and then more clouds later today, will be sandwiched around some midday clearing.  This clearing should let in some sun, but should do little to warm slopes.  Warming to avalanche terrain returns tomorrow, which may decrease today’s bridging strength, returning “Moderate danger” back into the mix. Generally, look for hard freezes at night with minor warm ups during the day initially this early April to let the snow slowly stabilize.

OTHER HAZARDS:  Long sliding falls are emerging as a hazard today. Icy, refrozen snow after the last two day warm-up will limit penetration of boots or skis. Crampons and an ice axe are recommended for travel on steeper slopes. Micro-spikes and other creeper style traction devices maybe helpful on some low angle approach summer trails, but they do not provide the security of crampons.  Also begin looking for undermined snow bridges and open holes, most likely found moving down the brook bed from the Bowl to the Little Headwall. The Harvard Cabin is closed for the season.

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. Posted 8:05a.m. 4-3-2014. A new advisory will be issued tomorrow.

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

2014-04-03-Print Version