Mt Washington NH Avalanche Bulletin

Forest Service Advisory for Mt Washington, New Hampshire

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Avalanche Advisory for Tuckerman and Huntington Ravines Posted: 8:37 a.m., Thursday, March 18, 2010

Tuckerman Ravine and Huntington Ravine currently have avalanche danger today. Natural avalanches are very unlikely and human triggered avalanches are unlikely except in isolated pockets. Normal caution is advised.

Increasing NW winds yesterday began lifting snow off the ground above treeline creating an aerial show of minor plumes on some ridge tops.

From lower on the mountain snow movement could be seen near Nelson Crag and the top of the northern gullies in Huntington; over the northern side of Tuckerman near the Lion Head gullies; and over the lower Boott Spur ridge into the "Fingerlings" of the Gulf of Slides. In the end snow movement began shutting down into the evening hours ultimately produced unimpressive results in the Ravines. Some very minor patches can be seen here and there but 99.9 percent of the forecast areas are old surface from the Sunday/Monday storm. A subdued diurnal recrystalization period occurred overnight due to clear below freezing conditions. This generated some sugary early facets below a crust of varying thickness depending on aspect. This will be mostly an annoyance for travel due to penetration depth rather than a stability concern today, but something to watch for the next snow loading event.

Most locations have seen traffic throughout our glorious warm week.

Visible ski tracks are beginning to pepper the mountain making it reminiscent of early spring skiing of years past. More seasonably warm temperatures today should bring another stream of folks up the mountain. If you do venture up, the two major things to consider include the baking south aspects and perhaps some new snow.

Solar gain will soften south facing aspects particularly in strong lee areas protected by NW and W winds. This softening induced some ski triggered loose wet sluffs of minor consequence yesterday, but they could be enough to entrain you and your skis if not managed well. These should not become large enough to pull out a lower slab however it is always something to keep in mind. High temperatures will continue to effect the cornices above Damnation and less so Yale. I would give these gullies some distance during the warmth of the day and/or the rain coming Sunday and Monday. Heat will also effect some thin hanging icicles here in there so it's time to consider the potential for some minor falling ice. I should also mention that clouds are expected to build in through the day keeping the heat penetration into the snowpack lower than yesterday. As they build the chance of snow showers is possible near the later half of the day so be prepared for the loading of new snow. It is not expected to be much but something to be aware of and watch as the day progresses. This may affect stability in some areas by tomorrow's forecast period.

The Lion Head Winter Route is open. The John Sherburne Ski Trail froze up again overnight but should become more reasonable as the day moves along.

Please Remember:

o Natural events such as avalanches are impossible to accurately predict in every instance. This Advisory is one tool to help you make your own decisions in avalanche terrain. It should be used along with safe travel techniques, snow stability assessments, an understanding of weather's effect on the snowpack, and proficiency in avalanche rescue.

o You should obtain the latest weather forecast before heading into the mountains. Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.

o For more information, contact the U.S. Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center or Hermit Lake Shelters or the HMC caretaker at the Harvard Cabin. A new avalanche advisory will be issued tomorrow and this advisory expires at midnight.

Christopher Joosen, Snow Ranger USDA Forest Service White Mountain National Forest

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