Avalanche Advisory for Wednesday April 9, 2014

This advisory expires at midnight

Tuckerman and Huntington Ravine have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.

AVALANCHE PROBLEM: New Wind Slabs are the primary avalanche problem today.  Yesterday snow generally ended during the morning followed by a rapid rise in temperature pushing a good deal of avalanche terrain close to 50F in the afternoon.  Following this warm fog the mercury fell with new snow showers beginning overnight, which is forecasted to continue this morning. This is causing new cold dry snow, on a NW wind, to load into slopes with an E facing component, hence the Wind Slab problem.

WEATHER:  The summit recorded 4.1” of snow and frozen forms, melting to 1.22” of water, in the past 24 hours.  Temperatures hit 38F, the 2nd highest mark of the season so far, which did a good job settling new wet snow from yesterday morning. The new snow overnight, coupled with a freefall of the mercury, will continue this morning. Eventually, ambient air temperatures will settle around 10F on the summit with any additional moisture being limited.  NW winds will increase all day gusting over 80mph late in the forecast period.

SNOWPACK:  In the past couple of days the summit has picked up 7.4” of frozen forms melting to 1.66” of water.  Following this dense, wet, mixed accumulation the temperatures soared to around 50F in avalanche terrain Tuesday afternoon.  Falling temperatures last night began the process of locking up this wet blanket by penetrating deeper into warm snow by the hour. Meanwhile, some light snow began intermittently bringing some new cold snow to E facing slopes, thinly covering some of the previous refreezing slabs.  This light snowfall is expected to continue this morning before a clearing trend begins.  The main issue today is any new cold slabs that may be developing in the two ravines.  This concern has caused us to issue today’s rating of Moderate.  There is some uncertainty exactly how this morning will play out due to the amount of light snow yet to come, an increasing wind, thick fog and blowing snow encapsulating the mountain.  A Moderate rating may be a conservative call for some areas, so anticipate hard crust, potentially breakable, to be as much of a safety issue as avalanches today.  Therefore, expect both a falling hazard, of both you and those above you, as well as new snow instabilities.  A likely scenario is hard conditions down low with areas of new snow in the highest strongest lee slopes.

OTHER HAZARDS: A falling hazard on frozen wind swept slopes is a real concern today so as always an ice ax and crampons are required to travel safely.  Also being ready for winter conditions with a temperature of 10F and hurricane force winds.  Despite the calendar, it is not spring in the mountains today.  Quality winter clothing should be part of your repertoire to avoid hypothermia.

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 7:55a.m. 4-9-2014. 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

2014-04-09 Print