Posted 8:13a.m., Tuesday, January 11, 2011
In Tuckerman Ravine the Chute, Center Bowl, Lip and Sluice have MODERATE avalanche danger today. Natural avalanches are unlikely and human triggered avalanches are possible in these areas. The remaining forecast areas in Tuckerman Ravine have LOW avalanche danger as do all forecast areas in Huntington Ravine. Natural and human triggered avalanches are unlikely in these areas but you should still watch for isolated pockets of unstable snow.
Everyone wants to talk about the approaching Nor’Easter but today we need to focus on the current conditions. The morning has been the first in quite some time where we’ve actually been able to get a good look at both ravines. They’ve been concealed behind a veil of clouds for the past few days while we got nickel-and-dimed with snowfall amounts averaging under an inch (2.5cm). During this period we had light winds from the S, strong winds from the W, and moderate winds from the NW that were perfect for loading. The critical variables have been wind speed and how much snow was available for transport during each of these periods. Howling winds stripped snow from many areas and deposited it down in the talus and trees below both ravines. This is especially true in Huntington where old surface is showing in nearly all areas. While much of each area forecasted with a low rating was stripped clean of new snow there are definitely protected spots where new snow has clung to the icy old surface. This snow may take a variety of forms from wind-sculpted sastrugi to soft slab. Wind-hammered snow is evident in many areas of Tuckerman and provides better stability than the smooth and creamy windslab but still not as good as the bulletproof old surface. Right Gully and Lobster Claw came down from a Moderate rating yesterday and Considerable the day before. These two areas are on the upper end of their current rating and good route-finding skills will allow you to navigate through without testing the areas of most concern on the climber’s left. Because spatial variability is high right now you’ll want to keep a close eye on conditions that change over short distances. The number one avalanche watch-out situation for the day is finding yourself traveling through smooth-surfaced snow where you actually penetrate deeper than your ankle. Such a situation is indicative of soft to medium hardness windslab overlying a slick bed surface. These conditions are not widespread but can be found if you go looking for them or go adventuring with your blinders on.
Even more of a concern than avalanches in many areas today is the potential for long sliding falls. Until we get some snow to cover the melt-freeze layer from 10 days ago the friction coefficient will remain low and a sliding fall could take you for a long and painful ride. Carry an ice ax in all open angled terrain and be ready to self arrest at the drop of a hat. Your body thanks you. Your body and your skis will also thank you if you wait until after the storm to ski the Sherburne. It has poor coverage for the time of year and we’ll need a solid foot of snow before I decide to ride even my rockboard down it again. It looks like we may get what we need tomorrow if we’re on the upper end of our forecasted snow accumulations. There’s a high degree of confidence that we’ll receive some snow but once you start discussing anything more than 4-6” people start to get a little squirrely. Keep your fingers crossed and your shrine to the snow god well stocked.
- 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.
Justin Preisendorfer, Snow Ranger
USDA Forest Service