Avalanche Advisory for Friday, December 13, 2013

A new advisory will be issued when conditions warrant or within 72 hours
Unless updated this advisory expires at 12:00 midnight Sunday, December 15, 2013

This is an early season GENERAL AVALANCHE ADVISORY for Tuckerman and Huntington Ravines. General Advisories are issued when isolated instabilities exist within the forecast areas. Forecasts using the 5-scale danger rating system will begin when snowfields and bed surfaces become more developed. Please remember that avalanche activity may occur before the issuance of a 5-scale danger rating forecast. As always, you will need to make your own snow stability assessments when traveling in avalanche terrain.

There are isolated snowfields in Tuckerman and Huntington Ravines that are growing in size and may harbor instabilities. Spatial variability is strong in these early season conditions. Climbers can expect to find potentially unstable slabs on benches beneath steep sections of rock and ice and in lee areas. The largest of these areas can currently be found in Sluice, Lip, Center Bowl, the Chute and Left Gully areas of Tuckerman and Central and Odell Gullies in Huntington. Other smaller snowfields are building in Pinnacle and possibly Yale. Increasing winds following Wednesday’s snowfall created pockets of windslab in both Ravines. Due to the “upside down” nature, that is dense slabs over lighter ones in the upper snow pack, these slabs may be reactive, even touchy, to human triggering. Add to this problem  2-4” of very light density snow falling and blowing Friday and cold temperatures slowing any natural stabilizing processes Friday night and Saturday. Additionally, 12” inches more snow predicted for Saturday night and Sunday will add to our stability issues and make a very challenging weekend to climb safely.  More reactive and much larger slabs in the Ravines on Sunday may even avalanche naturally without a human trigger.

Approximately 4-6” of new light density snow fell Wednesday on light winds. This snow did not bond well to cold, hard water ice or the ground, grass or rocks. New snow today (Friday) is already falling and is expected to continue at the rate of S-1 snow shower activity yielding 2-4”. West and northwest winds will blow at an effective loading velocity and will create windslabs on our existing thin snowpack. The good news is the snowfields are small in size due to meager snowfall so far this season. The bad news is the snowpack is so meager that numerous rocks and ice cliffs remain exposed making even a small slide potentially disastrous. Terrain traps are numerous and deep making burial a real possibility, even from smaller avalanches.

Today, temperatures on the summit are forecast to fall to -20F and rise to the mid-teens below zero tonight with winds in the “really cold” wind chill range. Check the weather forecast carefully as the next 48 hour period will change rapidly and frequently with passing weather systems. Trail conditions are challenging due to water ice, rocks and holes concealed by light density snow. Microspikes and crampons are necessary for most, if not all, trails. Saturday night’s storm may bring joy to Sherburne skiers although hidden hazards exist in the thin snowpack.

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 9:05 a.m., Friday, December 13, 2013. A new advisory will be issued when conditions warrant.

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

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