Avalanche Advisory for Thursday, March 20, 2014

This advisory expires  at midnight.

Tuckerman and Huntington Ravines have HIGH avalanche danger.  Natural avalanches are likely and human triggered avalanches are very likely. Very dangerous avalanche conditions exist and travel in avalanche terrain is not recommended. Avalanche hazard will remain elevated and even increase through the day.

AVALANCHE PROBLEMS: Storm Slabs will be the primary avalanche problem this morning. Wind Slabs, or problem #2, will continue to build due to increasing winds shifting from south to west. Travelling in avalanche runouts, like the floors of both ravines, is not recommended due to the risk and probability of natural avalanche activity.  Avalanches could be large and may step down into problem#3, older Persistent Slabs. Remember that increasing winds from the west this afternoon will have plenty of snow to build slabs and reload the gun barrels due to all the snow laying on the flat and expansive Alpine Garden.

WEATHER: Reduced visibility due to continued snowfall this morning, blowing snow all day and continued upslope snow showers in the afternoon will make it difficult to assess slopes and gauge your position relative to avalanche runouts. Southerly winds at 35-50 (56-80kph) mph will shift to the W and increase to 50-70 mph (80-112kph) in the early afternoon. Temperatures will fall back down to the mid teens. In addition to the 8.2″ (21cm) the summit has received so far another 1-3″ (2.5-7.5cm) is expected to fall through the day with a trace to 2″ (5cm) expected overnight due to upslope energy.

SNOWPACK: Temperatures at the start of this storm were in the low to mid teens F and winds were around 30-40 mph. Currently temperatures are approaching the mid-20’s F, much warmer than at the outset of snowfall. High winds blew in the 60’s mph, gusting in the 70’s, from midnight to 3am during the period of heaviest snowfall overnight. This wind direction and speed most heavily loaded gullies that face predominately north like parts of Odell, South, and the Escape Hatch.  Velocities also loaded and cross-loaded others like Pinnacle, Central, Chute, Left and Hillmans. Other areas received a blanket of new snow which has an equally disconcerting structure…lighter density snow with denser snow on top. The denser warmer snow is cohesive enough to create really touchy slabs prone to human triggering.  Continued snowfall and wind loading will create stress in the slab and increase the risk of human and natural triggering. These issues will increase on our main east facing slopes this afternoon as winds pick up and shift.  Of course, all of this speculation is based on weather data but if I were a betting man, I would lay my money on plenty of avalanche activity today, hopefully only of the naturally triggered variety. Remember that avalanche activity from the 18″ snowfall a week ago further smoothed and lengthened avalanche paths, buried many potential anchors points and generally brought all of our forecast areas into shape for larger avalanches to run in them. Today is a good day to find something else to do than travel in avalanche terrain on this fine, first day of Spring!

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 8:25am 3-20-2014. A new advisory will be issued tomorrow.

Franklin S. Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-03-20 Print