Avalanche Advisory for Friday March 15th, 2013

This advisory expires at midnight

Tuckerman and Huntington Ravines have CONSIDERABLE avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely.  Dangerous avalanches conditions exist.  Conservative decision making is essential.

The summit received 7.2” (18cm) of low density 6.25% snow in the past 24 hours. Frank and I were impressed by the variety of crystals we were seeing during the peak snowfall yesterday. Graupel, heavily rimed stellars, large 5mm clean unrimed stellars, with a needle or two thrown in here and there.  By 1pm in the afternoon we had a 4.0” blanket at Hermit Lake and it was still snowing.  I mention this fact because this morning the trail back up to Hermit Lake from Pinkham was fairly devoid of this fluffy blanket due to an increasing wind.  It’s mostly off in the woods somewhere, but we had a hard time finding it.

Joe and I got up into Huntington Ravine this morning hoping for a brief view of the terrain. This was optimistic as 60-70 mph winds were sending alpine snow pouring down into the lee of NW winds in both Ravines.  We got a glimpse of Huntington’s South and Odell, but only through a filter of blowing so a crisp view never materialized.  We did see enough to say confidently that both gullies had a lot of new slab.  As we came back over towards Tuckerman the same brief blurry views could be had of Dodge’s Drop and the Duchess.  We have a high degree of confidence that both avalanched from the top due to fracture lines and perhaps some debris.   All the evidence which includes, new low density snow, visible loading into lee areas and some new avalanche activity clearly states to me that we need to be concerned about natural avalanche potential.  We are in solid “Considerable” conditions today with very cold snappy new slabs in avalanche start zone hovering at about 0F (-18C).  These new slabs began their life as low density snow, so in some strongly protected locations you will find soft fist to four finger slabs.  In other places you will find slightly stronger slabs that were built by finer beat up crystals from alpine zones so expect variability in conditions and in your stability tests today.  The main concern is low visibility and the natural avalanche possibility above you today.  This natural potential may subside just a bit as a concern late in the day as winds decrease and shift.  It should continue to factor into your decisions today, but natural avalanches this morning is a higher possibility than near dusk.  Some of the largest snow fields from the Sluice, Lip and over through the Center Headwall in Tuckerman are also in the direct lee of the current NW, and later W, winds.  Expect these areas to be on the upper end of the Considerable rating having the greatest possibility for natural avalanche activity of all the forecasted locations in both Ravines.  There are a lot of nature’s warning flags up today to make you think “avalanches” so it’s a head’s up day to say the least.  Look for the weekend update to come out this afternoon and we’ll hint at our thoughts for avalanche problems for tomorrow.  There is not much question that we will have lingering stability issues that will keep our beacons, RECCO avalanche rescue detector, and avalanche dogs on high alert.  Talk to you this afternoon.

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 8:53 a.m. Month Year. A new advisory will be issued tomorrow.

Christopher Joosen, Snow Ranger
USDA Forest Service

2013-03-15 Print Version