Avalanche Advisory for Wednesday, February 12, 2014

This advisory expires at Midnight

Tuckerman Ravine has MODERATE and LOW avalanche danger. The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s Highway have Moderate danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low danger. Natural and human triggered avalanches are unlikely except in isolated areas of instability.

Huntington Ravine has MODERATE avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully and identify features of concern.

AVALANCHE PROBLEMS:  Wind Slab is the primary avalanche problem today. In addition to a little bit of new snow on Sunday and Monday winds have picked up some loose low density snow at the surface and redistributed this unconsolidated snow into new slabs.  Additionally, we have persistent slabs lingering in a variety of locations. These older slabs may feel quite strong underfoot, but if you find and impact a weakness, a large avalanche might result. Two of the most likely areas where you’ll find this are in Tuckerman’s Center Bowl and Huntington’s Central Gully.

WEATHER: Temperatures are expected to rise quickly out of sub-zero territory for the first time in several days.  Sun and clear skies will start the day with increasing clouds and a shifting, building wind moving from the NW to the SW.  This shift is in prelude to the substantial weather system moving our way determined to arrive tomorrow.  A “Winter Storm Watch” is currently in effect, likely to become a “Warning” during the next forecast period.  The track is coming into line, but the exact location will have a big effect in how much precipitation we receive.  Current predictions with human input is 8-12” while some of the automated outputs are producing up to 18”.  The track and the QPF, ranging from 1-2” of water will obviously have a great effect on how the snow piles up in the Presidential Range.  Current models have winds wrapping counter-clock wise on Thursday from the S to an E flow.  This E wind should dominate through the event become NE, N and eventually NW on Friday.

SNOWPACK: Denser wind slabs formed over softer ones, as well as loading over some areas of loose snow, are the main problems to be on the lookout today. This is often discussed as an “upside down” snowpack because it is the opposite of what you’d like to see as a recreationalist. “Right side-up” is dense down low becoming lighter at the surface which is often conducive to stability. The opposite, found in the field right now, is prone to being weak, ergo prone to possible failure.  The Center Bowl, Lip, and Sluice in Tuckerman and Central Gully in Huntington are good examples of primary locales harboring these weak slabs.

Yesterday’s discussion of a “smorgasbord of harder slabs ranging from P to 4F on the hand hardness scale” is accompanied by a buffet of sweet spots.  Unfortunately, sweet meaning bad, not good.  During recent field work we continue to be impressed by the variability and diversity of our snowpack weaknesses.  Digging into certain “sweet spots” we have exclaimed, “holy moly imagine if this was over there in that big steeper snowfield on the headwall!” Well…. It might be, however we have decided that we’re not going to check.  Recent data is clearly stating that there are still some time bombs out there. We need a reset button pushing event from mother-nature and the approaching storm coming could do it.  However, based on an expected E wind trending to the N, we might build up our meager S facing slopes, cleanout some NE aspects, but allowing some persistent issues to survive.  Be careful out there and stay vigilant as you travel to look for red flags.  Frequent reassessments will be important based on how spatially variable the snowpack continues to be.

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 753a.m. 2-12-2014. 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

2014-02-12 Print