Avalanche Advisory for Thursday, April 16, 2015

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Low avalanche danger. Natural and human-triggered avalanches are unlikely. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when traveling in avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

AVALANCHE PROBLEM: Cold temperatures returned to the mountain last night, helping to stabilize our snowpack. Freezing conditions help bond grains of snow together deeper in the snowpack and bridge over deep weak layers that may still exist. This leaves skier induced wet loose, also known as sluff, avalanches as our primary avalanche threat today. Steep slopes that have seen a lot of ski traffic generally have less of this type of problem. Areas that bake in the sun with no ski traffic have the greatest potential for a sizable sluff. The hazard of these heavy, wet piles of snow moving downhill comes from their ability to bulldoze you into bushes, rocks or over cliffs or to push your boards in expected directions.

OTHER HAZARDS: The typical spring hazards are beginning to show themselves.  Numerous areas of large ice have horizontal cracks forming and the Sluice ice, above Lunch Rocks, is already missing some chunks. Be aware of what is above you on a warm day and realize that eating lunch at Lunch Rocks puts you directly in the runout of large pieces of falling ice.  Today’s very warm temperatures will exacerbate this annual hazard. During this period of falling ice every year we do not recommend sitting at Lunch Rocks even though it may have a long tradition for you. The vast majority of icefall injuries over the past 50 years have occurred at Lunch Rocks also dubbed, “Icefall Rocks”.

The snow is slowly moving downhill as a unified mass and is pulling away from cliffs, creating crevasses. These may change quickly so anticipate them growing in size. Undermined snow is creating challenges for exiting the Bowl. While the Little Headwall is still skiable, there is open water both above and below. The best exit from the Bowl may involve walking to Connection Cache and possibly farther.

WEATHER: Once again sunny skies will rule with summit temperatures soaring to 40F, associated with winds increasing to from 40 to 60mph.  Tonight we will start a period of unsettled weather with mixed precipitation on the summits, potentially rain in avalanche terrain. This will continue Friday, and is currently forecast to persist on Saturday.  We’ll certainly get into this weekend weather forecast in tomorrow’s advisory and Weekend Update.  Until then enjoy the sun, wear your sunscreen, and keep spring hazards on the brain.

SNOWPACK: The near freezing conditions over the past couple of days helped to firm up and preserve our snow at Ravine elevations after last Friday’s rain and thaw. In Tuckerman Ravine, plenty of ski traffic has tested and compacted all our slopes and helped to ease our minds about wet slab avalanches. Being a generally cautious person, I wouldn’t leave my beacon, probe and shovel behind for lots of reasons.  Most of these are unlikely, but consider a large icefall or a subsurface meltwater blowout as an unusal, but not impossible, potential trigger. These are just of couple of reasons why we will continue to wearing our avalanche PPE through late spring.  As our snowpack melts, thin spots develop and firm or icy surfaces are exposed so be aware that an ice axe or self-arrest ski pole and crampons may be worthwhile weapons in your quiver.

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 Mount Washington Volunteer Ski Patrol, or the AMC at the Pinkham Notch Visitor Center and Hermit Lake.
  • Posted 7:45 a.m. Thursday, April 16, 2015. A new advisory will be issued tomorrow.

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

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