Avalanche Advisory for Tuesday, 4-10-2012

This advisory expires at 12:00 midnight, April 10, 2012.

All forecasted areas of Tuckerman Ravine have Considerable avalanche danger.  Natural avalanches are possible and human triggered avalanches are likely. 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.

This late in the season, avalanches might not be on your mind too frequently, so let’s review a critical component of an avalanche forecast, the danger rating. Today’s rating is Considerable, which means that naturally triggered avalanches are possible and human triggered avalanches are likely. For the backcountry traveler, this means that you don’t need to be high up on a steep slope to be at risk of getting hit with an avalanche. All you need to do is be in the potential runout zone and Mother Nature will take care of the rest. My hackles go up when I hear someone tell me they’re “just going up to check it out” or “not going very high.” Another part of the definition for Considerable danger relates to travel advice. It states, “Careful snowpack evaluation, cautious route-finding, and conservative decision making essential.” This is good advice for a day like today, when Mt. Washington remains in the grips of a multi-day winter storm. Currently, visibility is incredibly limited in the Bowl. Be honest with yourself, and if you don’t have the knowledge and experience to know exactly where you are in relation to avalanche paths, and to make these assessments and route choices, it would be a good idea to play it safe and avoid avalanche terrain.

Ok, I’m off my soapbox now, so on to the details. Over the last couple days, the upper parts of the mountain have received plentiful snow. Our storm board at Hermit Lake had 37cm (14.5”) on it as of 6:30 this morning. The summit has recorded more than that, coming in just under 48cm (19”) since snow began on Sunday afternoon. Additional snowfall will come today, though totals won’t be as great as they were yesterday. Much of the recent snow fell during strong winds that meandered in the N to W range of the compass rose. Lately they’ve been from the W and are forecasted to be in the 25-40mph (40-65kph) range, which will load and cross load snow into all forecast areas. Those areas in the strongest lee, such as the Sluice, Lip, Center Bowl, and Chute will pose the greatest threat. Right Gully and the Lower Snowfields have bed surfaces that are much less developed, so therefore will be in the lower end of the Considerable range.

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. We have not yet been able to assess these slide paths, so I won’t guarantee there is no avalanche hazard there today. The location with the greatest hazard here would be the snowfield traverse just as you arrive at treeline. I recommend choosing a different route, or traveling with the appropriate avalanche equipment and practicing safe travel techniques for avalanche terrain.

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.
  • 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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