Posted 7:55a.m., Friday, December 31, 2010
All forecast areas of Tuckerman and Huntington Ravines have Low avalanche danger today. Natural and human triggered avalanches are unlikely. Watch for isolated pockets of unstable snow in steep terrain. The Little Headwall, Lower Snowfields, and Escape Hatch remain “not posted” due to a general lack of snow in these areas.
Happy New Year’s Eve, everybody. What could possibly be a better way to end the year than with a strong surge of warm air from the south that will push summit temperatures well above freezing for a couple days? If nothing else, this is an ending that fairly represents the weather patterns of 2010—a bit of a roller coaster ride at times and always leaving us wanting more cold and snow. We got out yesterday into both ravines and found good stability in much of the terrain. Huntington was scoured down to a solid Low rating, as was much of Tuckerman Ravine. In the Center Bowl, Chute, and Left Gully the snow had been hammered by strong winds into a Styrofoam-like consistency. On the northern side of Tuckerman the story is a little different. This side was in the protected lee of the strong winds, which allowed for a little more deposition of new snow into isolated pockets that may still harbor instabilities. Also, temperatures, sun, and wind yesterday were just enough to keep surface snow cold in all but the most sheltered and sunny aspects, which hindered the stabilization of many of these areas. To further complicate things, at this point of the season we still don’t have full-winter snow coverage, so there is a lot of spatial variability in the bed surfaces, weak layers, and anchoring out there. Although there is a complex dance going on between all the different variables, the point is that we fit within the definition of a Low danger rating for all forecast areas. However, there are potentially unstable pockets to watch out for, so please don’t be lulled into the numerous human factors that can blind your decision making skills.
The warming that has already begun will continue today through tomorrow, with a little bit of rain thrown into the mix for New Years Day. This warming does have the potential to affect the snowpack, so we want it to be on your minds over the next two days. Warmth, whether from direct sun, rainfall, or general warmth, can cause slabs to lose strength as bonds between snow grains are broken down and water percolates into the snowpack. This loss of strength can correlate to an increase in avalanche danger. With such a strong degree of spatial variability around the ravine, we can’t rule out the potential for avalanches completely. Remember that Low danger means avalanches are unlikely, not impossible. Expect this to be more of a factor tomorrow than today, so if you’re making plans for Saturday, be sure to read the morning advisory. We’ll also be writing out first Weekend Update of the season this afternoon/evening, so check our website tonight as part of your planning process.
- 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.
- This advisory expires at midnight. 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