Avalanche Advisory for Friday, 2-10-2012

Expires 12:00 midnight, 2-10-2012

Tuckerman Ravine has both LOW and MODERATE avalanche danger.  The Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Lobster Claw, Right Gully, Left Gully, and Hillman’s Highway have Low avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features. The Lower Snowfields and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when conditions warrant.

Huntington Ravine has LOW avalanche danger.  Natural and human triggered avalanches are unlikely except in isolated terrain features. 

High pressure will stay in control once again today before we get a little break from the sunshine tomorrow. Today’s stability issues are the same ones we’ve been dealing with for a few days now. Over time, changes are taking place within the snowpack. Some of these are leading toward greater stability, and others are exacerbating the weak layer concerns. Exactly where you travel today will play a large role in whether or not you see unstable snow. In many areas of both ravines, snow stability is quite good. These are the areas we’ve rated Low danger for the past couple days. Those areas rated Moderate are currently sitting toward the lower end of the Moderate rating. However, we don’t have enough confidence in their stability to drop them to Low danger. The problem lies in the uppermost layer of crust that is buried beneath surface slabs and can act as a weak layer. The slabs sitting on the surface (i.e., on top of the crust) have a lot of strength, so it then becomes a question of whether or not a person’s impact would be enough to cause a failure of the weak layer. In such a lean snow year, the overall depth of snow is highly variable, as is the depth at which this crust is buried.

In the Sluice and Chute, much of the terrain has good stability. Below the narrows of the Chute and up the climbers’ left side offer good stability. The concerns lie above the narrows in the middle and right side. In the Sluice, you’ll find the most unstable snow tucked up underneath the ice just as the slope begins to steepen. The greatest stability concerns are still centered on the Lip and Center Bowl, in the steepest slopes below the ice. Overall, the crust is buried more deeply here, but there are numerous locations where the spatial variability could put you unknowingly on a thin spot. If you are able to put enough impact on the slab here, you might have a problem. You (or someone else) might also ski right over it without triggering anything. So I’ll remind you of the old adage, “tracks on a slope do not mean it is safe.” All it takes is the right trigger in the right location.

After a few sunny days, there is some weather heading our way for Saturday. Sadly, it’s trending farther away than we want, so not a lot of snow is forecasted. However, you should be expecting snow showers through the day Saturday. On Sunday, expect falling temperatures, increasing winds, and blowing snow. We’ll give you more detail on this in this afternoon’s Weekend Update, which you can find at our website. And finally, reports from the people who have tried to get into an out of the Little Headwall indicate that the slope itself is reasonably good skiing, but getting in and out of the area makes the experience not a worthwhile endeavor.

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 8:20am. A new advisory will be issued tomorrow.

Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

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