Avalanche Advisory for Wednesday, 4-11-2012

This advisory expires at midnight, Wednesday 4-11-2012

Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. The Sluice, Lip, Center Bowl, Chute, and Left Gully have Considerable avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely. Right Gully, Hillman’s Highway, and the Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.  Lobster Claw and the Little Headwall are not posted due to an overall lack of snow in these areas. Huntington Ravine is under a General Advisory. You will need to do your own snow stability assessments when using avalanche terrain in Huntington. A danger of falling ice exists, and will persist until it all comes down.

The summit recorded another 3.1” (7.5cm) of snow giving the higher mountain about 22” over the past 3 days.  Another 1-3” of snowfall is anticipated through the forecast period with reasonably light winds from the N and NNE at 10-25mph (16-40kph).  This may add a bit more light snow slab development near the ridgeline of several forecast areas; however most of the instability problems we face today have already been developed by loading on Monday and Tuesday.  This past loading occurred from a general W wind blowing between 35 and 75 mph over the last 72 hours. 

With the 5-scale danger ratings it is important to remember to put aside what you believe the key word (Extreme, High, Considerable, Moderate, and Low) means to you, but use it to link to the definition.  The “Considerable” rating means that naturally triggered avalanches are possible and human triggered avalanches are likely.  And “Moderate” states natural avalanches are unlikely and human triggered avalanches are possible.  These words reflect the likelihood of slope failure and not the size and destructive force.  I say this because unstable slabs associated with mid to late spring skiing are usually smaller than our current situation.  Realize we are going through a mid-winter avalanche/instability scenario so if slope failure occurs with our current slabs expect a number of them to run full path (aka- Big!).   Under the “Considerable” rating the size and distribution statement is flexible to address numerous situations depending on the actual snowpack weaknesses.  It reads, “small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.”  “Large avalanches in specific areas” covers our current situation fairly well from the Lip over to the Chute.  Be conservative and give the slopes some time to stabilize.  A little patience would be a prudent choice.  Warmer air over the next couple of days may increase our concerns briefly, but will ultimately help consolidate the snowpack.

As if avalanche danger wasn’t enough to make you stay out of the area, you need to know that the Center Bowl and Lip area have numerous deep crevasses. Expect all of these to be covered entirely by new snow, which makes for weak bridges that can collapse under your weight. You will not be able to assess this hazard safely and the consequences of falling into one of these crevasses are severe, so we recommend avoiding this area entirely. Hikers should not use Tuckerman Ravine to access the alpine zone and the summit of Mt. Washington. Also you should not descend down from these areas into the Ravine.

The Lion Head Trail does travel through known avalanche paths so having avalanche assessment skills will be important.  As with many trails that run through avalanche terrain in the Presidentials and the White Mountains that aren’t covered by avalanche forecasts you should be prepared to do stability tests and make your own evaluation.   

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, and the AMC at Pinkham Notch or Hermit Lake.  A new advisory will be issued tomorrow.

Christopher Joosen, Snow Ranger
USDA Forest Service, White Mountain National Forest

2012-04-11 Print Version