Avalanche Advisory for Sunday, January 12, 2014

This avalanche advisory expires at 12:00 midnight.

Tuckerman and Huntington Ravines have LOW avalanche danger.  Natural and human triggered avalanches are unlikely.

AVALANCHE PROBLEM:   We are quickly moving into having very limited avalanche problems.  The Wet Slab concerns from yesterday, and the early overnight, are transitioning to frozen concrete slabs due to dropping temperatures and high winds.

WEATHER: Over the past 24 hours the higher summits picked up +/- 1.4” (3.6cm) of rain and a trace of snow.  Summit temperatures peaked last night at 39F (3.9C) and has been falling ever since.  Currently, the summit of Washington is at 17 degrees F (-8.3C) and still falling with winds gusting to 80 mph from the W.  The mercury is expected to fall to about 10F (-12.2C) with winds gusting close to 100mph (160kph) before rising temperatures and slackening winds occur tonight. We will also get a very light shot of upslope snow this morning accumulating between a trace and an inch (2.5cm).

SNOWPACKThe current weather conditions are quickly sucking the heat out of the snowpack. We are rapidly freezing from the surface down as freezing makes its way deeper and deeper.  I would expect you will find both breakable crust and a hard crust that supports your weight.  As the day progresses you will find the tensile strength of near surface slabs increasing.  As this frozen layer gets thicker it will get stronger creating an eggshell, bridging over the wet draining snow below.  It’s almost not worth mentioning, but keep an eye on a very small pocket or two of new snow, depending on how much actual new snow we get this morning.  As skies clear we will let you know what avalanched or blewout during yesterday’s rain.

OTHER CONCERNS: Although avalanche potential is diminishing rapidly, a number of other hazards are taking center stage.

Long Falls– As the surface freezes hard and slick a fall in steep terrain will have you picking up speed extremely fast.  Instant self-arrest is critical!  Without an immediate stop it will be like trying to stop a Drag car at the strip with your old Schwinn brakes- near impossible.  Our lean snow cover will result in bouncing off many objects on the way down.

Ice Dams- As temperatures fall, and ice begins to grow, it will choke down flowing water beneath the surface snow and ice.  As this occurs hydraulic pressure can increase waiting to be released.  This is a particular hazard for ice climbers moving through gullies where water becomes constricted and backs up at ice bulges.  A tool swing or crampon kick can be all it takes to release a deluge of water and ice.  Historically climbers on Mount Washington have been hurt and killed by this phenomenon.

Breakable crust– Be cautious, particularly while moving downhill.  You may start to feel confident the snowpack will support your weight. Don’t!  A hidden bush just below the surface may still harbor enough heat to weaken the snow above and collapse beneath your feet.  This has both resulted in broken legs and long falls in the past.

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 8:20a.m. 1.12.2014. A new advisory will be issued tomorrow.

Christopher Joosen, Snow Ranger
USDA Forest Service

2014-01-12 Print