This advisory expires at midnight, Sunday 3-11-2012
All forecast areas of Tuckerman Ravine and Huntington Ravine have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.
All doubts can now be laid aside; spring has arrived. How do I know this? Every year around mid-March, a certain migratory species makes its presence known in Tuckerman Ravine. Stabilitus testorium, known to avalanche forecasters around the world as “volunteer stability testers”, are occasionally found in the eastern ravines during the height of winter. They become prevalent each spring, particularly on weekends. Yesterday a large flock descended on Tuckerman, testing slopes in numerous locations including the Center Bowl and Lip. While the biped variants had little success in their search for instabilities, one four-legged creature managed to release a couple minor propagating slabs while searching for a descent route through the Lip. Mostly though, the initial harbingers of spring were left to contend with sluff management on top of the dominant crust layer.
A quick recap of the weather over the last few days will explain a lot. Thursday night, warm temperatures prevailed with rain reaching all the way to the summit. Following this the mountain has received 3.4” (8.5cm) of new snow along with temperatures falling back below freezing. Some of this snow, about 2”, fell during very strong winds already and isn’t a big player in any stability concerns today. The last 1” or so fell yesterday morning with decreasing wind speeds and is where your avalanche eyes should be focused today. It is within this new snow where the small slabs were released and sluffs were created. There are isolated terrain features that have been able to hold onto pockets of new snow. Based on what was seen yesterday, there is a reasonably good chance these pockets are unstable. In addition to what was there yesterday, increasing wind speeds today have already begun to move some of this new snow around, obscuring and reloading some of the tracks laid down by yesterday’s ski traffic.
In the big picture, these areas of new slab on top of the crust are rather small. While they may not be large enough to deeply bury a person, they can certainly knock you off your feet. If that’s not bad enough, if you are standing in the runout admiring your tracks while one is kicked off by someone else, you’d better get out of the way in a hurry. Better yet, just don’t stand in the runout admiring your tracks. Move away to a safe area and enjoy the view without risking a severe and humiliating thrashing at the hands of a seemingly small slide.
Looking ahead to tomorrow, temperatures at the summit are projected to reach above freezing. If overnight lows don’t get below freezing, then we’ll have a prolonged period of warm temperatures, which may increase instability. The first warm days of the season can often be “heads up” kind of days. If you are thinking about a day in the ravine tomorrow, be sure to read the morning advisory.
- 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.
- 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