Avalanche Advisory for Wednesday March 6, 2013

Expires at midnight Wedneday 3-6-2013

Tuckerman and Huntington Ravines have MODERATE avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible.  Heightened avalanche conditions exist on specific terrain features.  Evaluate snow and terrain carefully to identify features of concern.  This is particularly relevant on south facing slopes.  The only exception to this is the Little Headwall which has LOW avalanche danger. Natural and human triggered avalanches are unlikely.

Another day of at least some snow accumulation continues the long trend of snowpack instabilities to look out for in both Ravines. Today is the 32nd day of the last 35 that we have picked up at least a little bit of snow, which makes me wonder if it’s the “Year of Moderate snowpack” on some ancient calendar.  The “Low” slats have come out less this season than I recall in recent memory due to continued upslope nickel and diming orographic precipitation.  (I’ll talk about this more on our website’s “The Pit” page later.)  Another 0.5 “ yesterday and about 1-2” today with an E wind gusting to 70 mph (112kph) this morning will cross load some S and N facing aspects. Most new loading will occur this morning before wind velocities decline through the day.  Expect some new slab predominately on the climber’s right of slopes facing S and climber’s left of those pointing N.  As an example the northerly facing portions of Odell, South gully and Escape Hatch in Huntington and Hillman’s and Left Gully in Tuckerman will probably see some new snow pillows develop in the lee of E winds on the upper climber’s left.  Of more concern are gullies and slopes being cross-loaded that face S. 

These south facing locales on the north side of the Ravines have been our big discussion point lately due to their complex snowpack.  Numerous suncrusts at different depths and new slabs deposited by several days of NW, N and NE winds have made these aspects the main avalanche concern on Mount Washington.  Of the two Ravines, Tuckerman’s south pointing components of the Lobsterclaw, Right Gully, Sluice, and Lip-Center Bowl transition are the places requiring the most attention with avalanche eyes fully open.  Although the southern facing aspects in both Ravines don’t quite meet the criteria for a “Considerable” rating expect them to be just below this, on the upper end of the Moderate definition.  However, the exact definition of “Moderate” in regards to avalanche likelihood, distribution and consequences still reflects our current situation most accurately.  The choice to drop these locations by a rating came from our field time in these areas yesterday and the overnight and forecasted weather today.  Looking ahead, we are on the northern fringes of another storm system focused south of the White Mountains, but anticipate more snow in the mountains Thursday heading into Friday morning.  Expect more of the mid-range danger scale ratings in the prelude to the weekend.

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 8:00 3-06-2013. 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

2013-03-06 Print Version

Got Upslope? #1

Upslope Snow? Orographic Snow? Tr-2”? Anyway you name it a northwesterly flow and a little bit of valley moisture produces the often discussed “ 1-3” today, trace-2” tonight, and 1-3” tomorrow”.  Upslope snow and its ability to drop several inches of low density snow in a day keeps us on our toes.  Couple 3-4 inches (7.5-10cm) of 2-4% (20-40 kg/m3) density snow with Washington’s famous high winds and we’ve got avalanche problems on what our western counter parts would consider much to-do about nothing.  But here in the Presidentials I would say it is one of the main drivers of our Moderate and sometimes Considerable avalanche danger rating forecasts. 


Over the next 2-3 weeks we will have a number of contributors, such as the Mount Washington Observatory summit crew, Snow Rangers, perhaps a DOT Snow Plower, a local Snowcat operator, and our Ravine Caretakers who wear many hats, one being professional snow removal technicians.  All of it together will help us better understand the upslope enigma.   So… get ready for this orographic colloquium-symposium-conference-workshop thread!  Keep an eye out for GOT UPSLOPE? #2