Expires 12:00 midnight, 1-30-2012
Tuckerman Ravine has Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. The only exception to this is Right Gully which has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted.
Huntington Ravine has Considerable, Moderate, and Low avalanche danger. Central, Pinnacle, Odell, and South Gullies have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Yale Gully has Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. North, Damnation, and the Escape Hatch have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.
The past few days have been rather interesting from a forecasting perspective. Since Friday’s warm rain event, the mountain has seen roughly 6” (15cm) of new snowfall, mostly falling intermittently with breaks of nicer weather in between. From midnight Saturday through this morning, about 2” (5cm) of light density snow has fallen on the summit and at Hermit Lake. While the general trend today is for snow shutting down and visibility clearing, winds will have little difficulty moving the recent snowfall from upper elevations into the ravines. This new loading will continue through today since wind speeds will be on the rise. Today’s Considerable rating is based largely on the potential for naturally triggered avalanches in many areas. Early in the day, poor visibility will limit your ability to make visual assessments of where loading is taking place. You can reasonably assume most aspects in both ravines are receiving some loading. Those aspects facing due E, such as the Lip, Center Bowl, Central Gully, and Pinnacle Gully, are going to be getting the direct load, but we have no reason to believe cross loading will not be taking place in most other areas. As always seems to be the case, expect a high degree of spatial variability as you move from one location to another.
One factor going into our decision making today is the prior development of snowfields in certain areas. In a “normal winter,” Right Gully would probably have been rated Considerable today instead of Moderate. However, the snowfields at the top start zone are really just filling in. There are still sufficient trees to act as anchors in a lot of this terrain. If you venture into larger snowfields within this gully, your chances of seeing stability issues will increase. Similarly, North Damnation, and the Escape Hatch are rated Low primarily because of the lack of snow in the upper avalanche start zones. You may find locations within these forecast areas where windblown snow has collected, and you should assess these carefully or avoid them altogether.
Clearing skies today will hopefully provide mountain travelers the ability to see where they’re going, and use visual clues to help make better informed route choices. Keep in mind that blue skies do not equate to stable snow, especially when additional windloading is taking place above you.
The Sherburne Ski Trail is doing quite well right now. The breakable crust from Friday night has been broken by the weekend traffic. It’s now most similar to packed powder with a handful of icy spots near the bottom. This should continue to improve with additional snow today and tomorrow.
- 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 8:30am. 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