Avalanche Advisory for Sunday, 2-26-2012

This Advisory expires at Midnight Sunday, 2-26-2012

Tuckerman and Huntington Ravines have CONSIDERABLE avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely. Dangerous avalanche conditions exist.  Cautious route finding and conservative decision making is essential.  The only exception to this rating is the Little Headwall, which has Moderate danger.  Thin areas and some holes into the brook still exist

While the storm wrapped up in the valleys yesterday upslope snow kept chucking snow in the high mountains giving up an additional 4.8” (12cm) on the summit.  Very high winds didn’t quite get to where we thought they might, but it came darn close, gusting over 100mph (160kph) with a maximum of 107mph.  Snow showers finally shut down early this morning. High velocities for most of today will continue with some loading.  The whipped low density crystals are being pulverized, creating an aerosol shield over the mountain.  Visibility is still very limited so we are getting anxious to see the aftermath of this storm which delivered 10” to the summit and about 13” (32.5cm) at Hermit Lake.  A brief window of visibility allowed us to see a debris pile at the bottom of Hillman’s Highway and a large crown line in the Tuckerman Bowl through the Lip before a veil of secrecy cloaked the Ravine once again.  Being conservative for at least another day would be a good idea.

Between the continued loading and the inability to completely substantiate what avalanched and what is still on steep slopes waiting, we can’t rule out the possibility of natural avalanches today.  In Tuckerman, I believe we have just come down from yesterday’s “High” rating so expect a solid or upper end of “Considerable” to be the starting point in numerous locations this morning.  In Huntington, you should find much more variable conditions with scoured surfaces in some of the ‘wind tunnel’ sections of gullies and pillowed up snow in others.  The lower end of the Considerable rating is the probable situation in this, more northern Ravine.  Again, loading is continuing due to high NW winds so if snow movement does shut down it won’t happen until very late in the day.  Cold air below zero F (-18C) will keep slabs from consolidating much, allowing instabilities to survive particularly in areas sheltered from high winds.  Other slopes exposed to today’s high winds may be kept scoured clean and will likely continue to become wind hardened, helping stability slowly increase.   Ultimately, you should find a high degree of slope scale spatial variability; hard old surfaces in some locales; hard new Styrofoam in others; and deeper new soft slabs as you get into the strong lee of protected terrain.  I say all this because with limited visibility you won’t have sight to aid your assessment of what is above you.  Expect differences, changing surface conditions and varying degrees of snow instability.  It is also Sunday, the last day of vacation week, so expect a number of human triggers to be running around.  If you are one of those triggers descending into soft slab on a popular route anticipate the potential of others below you shrouded by clouds and snow.  Also expect a brutal day above treeline with negative temperatures and very high winds.    

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 8:35a.m. 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
www.mountwashingtonavalanchecenter.org

2012-02-26 Print Version