Posted 8:15a.m., Saturday, January 15, 2011
Tuckerman Ravine: The Lobster Claw, Right Gully, Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Left Gully and Hillman’s Highway have Low avalanche danger. Natural and human triggered avalanches are unlikely. The Little Headwall and Lower Snowfields are not posted due to a lack of snow in these areas.
Huntington Ravine: North, Damnation, Yale, Central, and Pinnacle gullies have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Odell and South gullies have Low avalanche danger. Natural and human triggered avalanches are unlikely. The Escape Hatch is not posted due to a lack of snow in this area.
After a fairly uneventful 24 hours of weather, avalanche conditions for the ravines today will be similar to yesterday with a mix of Moderate and Low danger. Wind speeds yesterday were in the single digits on the summit during the day, making the Bowl seem eerily calm and allowing us to get some good hands-on stability data. The latest storm brought about 16” (41cm) of snow to Hermit Lake, but it came with a slightly atypical wind pattern. What we have now are conditions that range from boilerplate hard old surface in the areas that were the most wind scoured (e.g. below the Chute and in much of Left Gully), to deep soft slab in heavily protected areas (e.g. some of the midsections of Right Gully and Lobster Claw). Spatial variability is once again a strong factor in snow stability. This means you’ll find that stability and conditions change quickly as you move around in the terrain. Although the variability is strong, there are a couple of consistent factors to help aid your decision making.
One consistency is related to which areas the recent snow was loaded into. Slopes and gullies on the northern side of the ravines received much more loading than those on the southern sides. Slopes in the central sections of both ravines had some cross-loading as well. Hillman’s Highway and Left Gully may have actually lost snow thanks to strong E and N winds. It’s the same story for Odell and South gullies in Huntington. The areas of most concern are those where new snow was loaded more deeply and was beyond the reach of yesterday’s solar gain. The sun wasn’t strong enough to affect the deeper instabilities or the aspects that aren’t directly facing south. The list of locations to watch out for includes the E-facing aspects in the Lip and Sluice, various parts of Right Gully and Lobster Claw, the tops of Yale, Damnation, and North, and the snowfields leading up to Central and Pinnacle. While this list isn’t comprehensive, my hope is that it helps you understand the degree of spatial variability that exists out there right now. You’ll need to continually be assessing stability as you move.
Another consistency is the New Year’s crust you’ll find underneath any new snow. Its depth will vary, but wherever you encounter it, the stuff is rock solid. Bury it under energetic slab and it can make for a great bed surface. In much of the Center Bowl and Chute this is less of a concern as it has bonded pretty well to the stiff slab above it. It can also be found at the surface in some locations; in these areas you’ll need to be ready to self-arrest immediately to avoid a rapidly accelerating fall.
- 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