Avalanche Advisory for 2-20-2012

Expires 12:00 midnight, February 20, 2012

Tuckerman Ravine has MODERATE and LOW 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.

All forecast areas of Huntington Ravine have LOW avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

It’s only fitting that on the Washington’s birthday holiday, the weather clears out and allows the mountain to show off a little bit. There are ample opportunities for recreating in Low avalanche danger today. All of Huntington is rated Low, and about half of our forecast areas of Tuckerman are as well. Surface conditions in these areas are mostly wind-scoured or strongly wind-effected. You could probably find an isolated pocket of unstable snow if you really wanted to, so don’t let your guard down 100% just yet. Although these areas are rated Low, it’s not the same kind of Low we typically get in the springtime melt-freeze cycles.

The recent 5.4” (13.7cm) of snow that has fallen on Mt. Washington over the past several days has loaded into lee aspects of Tuckerman. This includes an unexpected upslope event yesterday afternoon that brought another half inch of snow. Some of what we saw yesterday in the field showed us that there was a weak interface between layers of this new snow. We found this in Right Gully, the Sluice, the Chute, and down low under the Lip. We believe this is from changes in winds and snow crystal type during the snowfall on Saturday. Although the weak layer was present, in most areas where it was found, we didn’t find a strong tendency for propagation. I suspect this has changed for the worse overnight, due to the slight wind effect causing an increase in cohesiveness over time. The areas of most concern today are in the well-protected strong lee, such as underneath the Lip, under the ice in the Center Bowl, and just above the narrows on the climber’s right side of the Chute. Yesterday a group of climbers worked their way up the middle of the Sluice. Their tracks are gone today, indicating some loading did take place yesterday. On the whole, there is a range of stability within today’s Moderate rating. Your exact choice of route will determine whether you’re in the lower end of Moderate or venturing into the upper end of Moderate.

Yesterday three people were killed in an avalanche in Steven’s Pass, Washington. According to news reports, a total of 13 skiers were involved in the incident, four of these were carried a long distance. I mention this as a reminder that we all need to be mindful of what others are doing nearby us. Mt. Washington is a very busy place, especially this weekend. The psychological factors at work in backcountry recreation can be incredibly strong. Two things you should always remember here on Mt. Washington: 1) just because there is a bootpack established does not mean the slope is safe, and 2) whenever possible, exposing only one person at a time to avalanche hazard is a good idea. There’s a lot more to know than just these points, but remember these and your avalanche education will be off to a good start.

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 8:35am. 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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