Avalanche Advisory for Thursday, 4-4-2013

 This advisory expires at Midnight

Tuckerman and Huntington Ravines have MODERATE avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions on specific terrain features exist.  Evaluate snow and terrain carefully to identify these concerns.

It ain’t over until the…..well you know the rest.  Winter keeps producing and this last weather maker is no exception.  9+” of snow with extreme winds for 2 days did quite a job filling in the Ravines and giving us some good avalanches.  Winds between 100-127mph for hours on end not only moved new snow into lee areas but also eroded alpine snow to send large volumes into the eastern flanks of Washington.

In Tuckerman, a Hillman’s Highway avalanche ran around the dogleg and out of view.  The “Y” in Hillman’s plumped up very nicely as did the upper climber’s right.  In the main bowl we picked up truckloads of snow, at first glance lots of terrain features visible this weekend are now covered.  I suspect some avalanche activity occurred however no obvious fracture lines are visible.  I would generally say that most of this event’s snow stayed where we want it, up on the slopes, compared to down on the flats after avalanching.  Today you will find variable conditions from very hard slab (aka steel slab) to degrees of softer snow in strong lee areas. High winds produced some visually impressive wind rip features.  The upper reaches of the Sluice, Lip and Left gully were clearly affected by high winds.  As the winds let up, new snow laid in, resulting in numerous areas of smooth, softer,  surface conditions.  The most probable areas of widespread softer slab are those aspects with a south facing component such as the Lobster Claw over to the lower Sluice.  These slopes are more heavily protected from NW winds by the terrain.  You will likely find a variety of stability falling with the Moderate definition.  You will find some harder slabs on low angle terrain falling within the lower half of Moderate, while softer slabs on steeper slopes may fall in the upper half of the rating.  Be attentive to varying stability as you travel.  We will get into Tuckerman later today to better determine the overall situation in regards to the thickness of soft slabs and the potential for fractures to propagate.

Over in Huntington we are barely at “Moderate” but feel it is most appropriate due to stability issues down low on the approaches and a number of pockets that go wall to wall within a given gully.   Although certainly present, we expected to see more scouring after the winds the mountain recently experienced. The upper half of Central stands out as the most heavily scoured however the slope below the ice harbors some stability concerns.  As far as concerns down low the approaches to the northern gullies under North, Damnation, and Yale have the most new snow. Like the south facing slopes in Tuckerman they were most protected by NW winds.  Winds will fall, but will continue to keep the day and snow cool even under clear skies.  As the high pressure becomes established winds will settle in between 40-60 mph later today.

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 8:45 a.m. April 4, 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

2013-04-04 Print Version