Posted 8:15a.m., Sunday, February 13, 2011
Tuckerman Ravine: Sluice, Lip, Center Bowl, and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Lobster Claw, Right Gully, the Chute, Left Gully, the Lower Snowfields, and the Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely.
Huntington Ravine: All forecast areas of Huntington have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.
Yesterday’s snow showers deposited just over an inch of new snow at the Hermit Lake snow plot. Winds on the Summit increased out of the west through the day with gusts over 100 mph (161 kph) late last night. Even though these winds did not have much new snow to work with, they were determined to make the most out of it. This effort resulted in several small natural avalanches that occurred in the Chute, Center Bowl, Lip and Sluice in Tuckerman. These areas are the most protected from west winds and were able to offer a place for the wind blown snow to collect. Areas that are not as protected had their scant amounts of new snow swept away by the strong winds. Huntington Ravine is pretty well scoured out as is Left Gully in Tuckerman Ravine. For today, there are three snow stability issues to be on the lookout for. The first is any new wind slab deposited by yesterday’s weather that did not avalanche. These slabs are going to be relatively thin and could be easy to trigger. You will find them in very sheltered areas of west winds. Based on the size of the recent avalanches that occurred in Tuckerman, I would expect new avalanches that occur in the new snow to be pretty small. The second stability issue is wind slab that is left over from last week. These have been responsible for keeping some forecast areas in Tuckerman at Moderate for a while now. The good news is that these slabs are likely to be difficult to trigger based on their high density and the fact that they have been around for several days and have had some time to settle. The bad new is that if you are able to get one go it could be a sizable slide that you wouldn’t want to be in. Examples of these slabs can be found in Hillman’s Highway and in the Center Bowl, Lip and Sluice. The third snow stability issue you need to be aware of today is incoming weather that may increase avalanche danger in all forecast areas by the end of the day. Low pressure will turn our blue bird day into clouds and snow with 1-2″ (2.5 to 5 cm) of accumulation forecasted by the end of the day. West winds between 50 and 75 mph (80 and 120 kph) will be transporting this snow into the Ravines and new wind slabs will begin to develop. This is similar to what happened yesterday but the winds aren’t going to be as strong. This will allow new slabs to develop in many areas and could start to become problematic by the end of the day. Light snow will continue overnight and tomorrow with a total of 2-4″ (5 to 10 cm) expected by the end of tomorrow. As a result, expect elevated avalanche danger 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.
- This advisory expires at midnight. A new advisory will be issued tomorrow.
Brian Johnston, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856